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Articoli di riviste sul tema "Hole spin quantum bit"

Autore: Grafiati

Pubblicato: 5 ottobre 2024

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1

Mäkelä, Jarmo. "Wheeler’s it from bit proposal in loop quantum gravity". International Journal of Modern Physics D 28, n. 10 (luglio 2019): 1950129. http://dx.doi.org/10.1142/s0218271819501293.

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As an attempt to realize Wheeler’s “it-from-bit proposal” that physics should be reduced to simple yes–no questions, we consider a model of loop quantum gravity, where the only allowed values of the quantum numbers [Formula: see text] at the punctures [Formula: see text] of the spin network on the spacelike two surfaces of spacetime are [Formula: see text] and [Formula: see text]. When [Formula: see text], the puncture is in the vacuum, and it does not contribute to the area of the two surface, whereas when [Formula: see text], the puncture is in an excited state, and the allowed values of the associated quantum number [Formula: see text] are [Formula: see text] and [Formula: see text]. As a consequence, the spin network used as a model of spacetime is analogous to a system of particles with spin [Formula: see text], and every puncture carries exactly one bit of information. When applied to spacetimes with horizon, our model enables us to find an explicit expression for the partition function of spacetime. Using this partition function we may, among other things, obtain the Bekenstein–Hawking entropy law for black holes. When applied to cosmological models with horizon, the partition function predicts a cosmic phase transition in the early universe, where the cosmological constant went through a dramatic decrease and the matter of the universe was created out of the vacuum.

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2

Combescot, Monique, e Shiue-Yuan Shiau. "From spherical to periodic symmetry: the analog of orbital angular momentum for semiconductor crystals". Journal of Physics: Condensed Matter 34, n. 20 (4 aprile 2022): 205502. http://dx.doi.org/10.1088/1361-648x/ac5867.

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Abstract The angular momentum formalism provides a powerful way to classify atomic states. Yet, requiring a spherical symmetry from the very first line, this formalism cannot be used for periodic systems, even though cubic semiconductor states are commonly classified according to atomic notations. Although never noted, it is possible to define the analog of the orbital angular momentum, by only using the potential felt by the electrons. The spin–orbit interaction for crystals then takes the L ^ ⋅ S ^ form, with L ^ reducing to L ^ = r ^ × p ^ for spherical symmetry. This provides the long-missed support for using the eigenvalues of L ^ and J ^ = L ^ + S ^ , as quantum indices to label cubic semiconductor states. Importantly, these quantum indices also control the phase factor that relates valence electron to hole operators, in the same way as particle to antiparticle, in spite of the fact that the hole is definitely not the valence-electron antiparticle. Being associated with a broader definition, the ( L ^ , J ^ ) analogs of the ( L ^ , J ^ ) angular momenta, must be distinguished by names: we suggest ‘spatial momentum’ for L ^ that acts in the real space, and ‘hybrid momentum’ for J ^ that also acts on spin, the potential symmetry being specified as ‘cubic spatial momentum’. This would cast J ^ as a ‘spherical hybrid momentum’, a bit awkward for the concept is novel.

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3

Jiang, Ao, Shibo Xing, Haowei Lin, Qing Chen e Mingxuan Li. "Role of Pyramidal Low-Dimensional Semiconductors in Advancing the Field of Optoelectronics". Photonics 11, n. 4 (15 aprile 2024): 370. http://dx.doi.org/10.3390/photonics11040370.

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Numerous optoelectronic devices based on low-dimensional nanostructures have been developed in recent years. Among these, pyramidal low-dimensional semiconductors (zero- and one-dimensional nanomaterials) have been favored in the field of optoelectronics. In this review, we discuss in detail the structures, preparation methods, band structures, electronic properties, and optoelectronic applications (photocatalysis, photoelectric detection, solar cells, light-emitting diodes, lasers, and optical quantum information processing) of pyramidal low-dimensional semiconductors and demonstrate their excellent photoelectric performances. More specifically, pyramidal semiconductor quantum dots (PSQDs) possess higher mobilities and longer lifetimes, which would be more suitable for photovoltaic devices requiring fast carrier transport. In addition, the linear polarization direction of exciton emission is easily controlled via the direction of magnetic field in PSQDs with C3v symmetry, so that all-optical multi-qubit gates based on electron spin as a quantum bit could be realized. Therefore, the use of PSQDs (e.g., InAs, GaN, InGaAs, and InGaN) as effective candidates for constructing optical quantum devices is examined due to the growing interest in optical quantum information processing. Pyramidal semiconductor nanorods (PSNRs) and pyramidal semiconductor nanowires (PSNWRs) also exhibit the more efficient separation of electron-hole pairs and strong light absorption effects, which are expected to be widely utilized in light-receiving devices. Finally, this review concludes with a summary of the current problems and suggestions for potential future research directions in the context of pyramidal low-dimensional semiconductors.

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4

Hartmann, Jean-Michel, Nicolas Bernier, Francois Pierre, Jean-Paul Barnes, Vincent Mazzocchi, Julia Krawczyk, Gabriel Lima, Elyjah Kiyooka e Silvano De Franceschi. "Epitaxy of Group-IV Semiconductors for Quantum Electronics". ECS Meeting Abstracts MA2023-01, n. 29 (28 agosto 2023): 1792. http://dx.doi.org/10.1149/ma2023-01291792mtgabs.

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Epitaxy of group-IV semiconductors is a key enabler for quantum devices. Low temperature epitaxy can be used to deposit Si:B layers with boron concentrations so high that they are superconductive (ECS Transactions 98(5), 203 (2020)). Tensily strained Si layers sandwiched between relaxed Si0.7Ge0.3 layers behave as quantum wells for electrons, enabling electron spin quantum bit (qubit) fabrication. Purified 28Si without deleterious 29Si isotopes (with a nuclear spin) are ideal as the core of fully-depleted, multiple gate transistors for qubits. Compressively-strained Ge layers sandwiched between relaxed Si0.2Ge0.8 layers can confine a two-dimensional hole gas (2DHG) offering an emerging pathway to hole-spin qubits. In the following, we will focus on the latter two subjects. We will show how we succeeded in growing 28Si layers with the following concentrations: 28Si isotopes > 99,992%, 29Si isotopes < 0.006% and 30Si isotopes < 0.002% (Journal of Crystal Growth 509, 1 (2019)). Such values can instructively be compared to those in natural Si: 28Si: 92.223%, 29Si: 4.678% and 30Si: 3.092%. The availability and cost of isotopically enriched 28SiH4 is a major difficulty, however. We thus quantified the impact of growth temperature and HCl mass-flow on the Si growth rate. At high temperature, above 850°C, we reached a silane supply limited regime with a good decomposition efficiency, high growth rates (> 100 nm min.-1 for the SiH4 mass-flow selected) and almost no impact of the HCl flow. There was otherwise, below 850°C, a H- and Cl-surface desorption limited regime, with a lesser decomposition efficiency and Si growth rates which dropped as the temperature decreased and/or the HCl mass-flow increased. Thick 28Si layers should be grown at high temperature, while low temperature epitaxy should be limited to the deposition of thin 28Si layers on top of SiGe sacrificial layers (28SOI fabrication with a bonding-etch back approach) or the thickening of SOI substrates (to avoid elastic or plastic relaxation/dewetting). We otherwise fabricated c-Ge/SiGe heterostructures for hole spin qubits. We first grew at 850°C, 20 Torr and with a SiH2Cl2 + GeH4 chemistry, SiGe virtual substrates (VS), with a gradual ramping-up of the Ge concentration (to confine misfit dislocations) and a capping with 3 µm thick constant composition layers. Reciprocal Space Maps around the (004) and (224) X-Ray Diffraction (XRD) orders gave us the Ge concentration in those SiGe caps (73.8% and 78.7%) and their macroscopic degrees of strain relaxation (102.0 and 102.5%). The surface cross-hatch, e.g. the regular array of undulations with a 1-2 µm spatial wavelength because of a periodic strain field in VS, was suppressed using Chemical Mechanical Polishing (CMP). We then grew on top of the polished SiGe VS, at 500°C, 20 Torr and with a SiH2Cl2 + GeH4 chemistry, {100 nm thick SiGe 74% or 79% / 16 nm thick compressively-strained Ge / variable thickness SiGe 74% or 79% overlayer / Si 2nm cap} stacks. The parameter that changed was the SiGe overlayer, with 22, 33, 44 or 55 nm thicknesses probed. Compared to polished surfaces, a slight surface roughening was observed for the SiGe stacks, larger for the SiGe 74%/c-Ge than for 79%/c-Ge stacks. Thicker SiGe overlayers yielded smoother surfaces. We ascribe these surface undulations, with a ~ 100 nm wavelength, to an elastic relaxation of the compressive strain in the c-Ge layers. XRD showed that those stacks were pseudomorphic, with the same in-plane lattice parameter for the c-Ge layers than that of the SiGe VS underneath. Energy Dispersive X-ray spectroscopy (EDX) mapping of the whole structure showed that the Ge grading was rather linear with, as intended, a 10% Ge/µm grading. Cross-sectional Transmission Electron Microscopy (TEM) showed the presence of numerous misfit dislocations in the graded layer and none in the thick Si0.21Ge0.79 / c-Ge stack on top. A slight Ge concentration increase, by a few %, was measured by EDX at the CMP location, with a perfect crystallinity in the stack grown on top. The 16 nm thick c-Ge layer itself was perfectly monocrystalline, with a 1-2 bi-atomic layer roughness at c-Ge/SiGe interfaces, no in-plane deformation compared to the surrounding SiGe and an out-of-plane deformation of 1.5% from Precession Electron Diffraction. Magnetotransport measurements in Hall-bar devices were performed at 4.2 K to assess the electrical properties of the 2DHG in the grown SiGe/c-Ge heterostructures. At low magnetic field, a hole mobility of 1.2 x 105 cm2 V-1 s-1 was obtained for a hole density of n2DHG = 3.7x1011 cm-2 in the c-Ge/SiGe 79% 55nm sample, whereas quantum Hall effect plateaus and Shubnikov-De-Haas oscillations were observed at higher fields. Figure 1

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5

Marie, X., T. Amand, P. Le Jeune, M. Paillard, P. Renucci, L. E. Golub, V. D. Dymnikov e E. L. Ivchenko. "Hole spin quantum beats in quantum-well structures". Physical Review B 60, n. 8 (15 agosto 1999): 5811–17. http://dx.doi.org/10.1103/physrevb.60.5811.

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6

Oguri, A., K. Yamanaka, J. Inoue e S. Maekawa. "Quantum spin-liquid state with a hole". Physical Review B 43, n. 1 (1 gennaio 1991): 186–92. http://dx.doi.org/10.1103/physrevb.43.186.

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7

Ferreira, R., e G. Bastard. "Hole “Spin” Relaxation in Semiconductor Quantum Wells". Europhysics Letters (EPL) 23, n. 6 (20 agosto 1993): 439–44. http://dx.doi.org/10.1209/0295-5075/23/6/010.

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8

Zinov’eva, A. F., A. V. Nenashev e A. V. Dvurechenskii. "Hole spin relaxation in Ge quantum dots". Journal of Experimental and Theoretical Physics Letters 82, n. 5 (settembre 2005): 302–5. http://dx.doi.org/10.1134/1.2130917.

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9

Baylac, B., X. Marie, T. Amand, M. Brousseau, J. Barrau e Y. Shekun. "Hole spin relaxation in intrinsic quantum wells". Surface Science 326, n. 1-2 (marzo 1995): 161–66. http://dx.doi.org/10.1016/0039-6028(94)00743-8.

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10

LI, ZHONG-HENG. "QUANTUM ERGOSPHERE AND HAWKING PROCESS". Modern Physics Letters A 14, n. 28 (14 settembre 1999): 1951–60. http://dx.doi.org/10.1142/s0217732399002029.

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We study both spherically symmetric and rotating (Kerr) nonstationary black holes and discuss the radiation of these black holes via the Hawking process. We find that the thermal radiation spectrum of a nonstationary black hole is obviously dependent on the spin state of a particle and is different from the case of a stationary black hole. This effect originates from the quantum ergosphere. We also find that the field equations of spin s=0,1/2,1 and 2 can combine into a generalized Teukolsky-type master equation with sources for any spherically symmetric black hole.

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11

BOSE, INDRANI, e AMIT KUMAR PAL. "QUANTUM DISCORD, DECOHERENCE AND QUANTUM PHASE TRANSITION". International Journal of Modern Physics B 27, n. 01n03 (26 novembre 2012): 1345042. http://dx.doi.org/10.1142/s0217979213450422.

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Quantum discord is a more general measure of quantum correlations than entanglement and has been proposed as a resource in certain quantum information processing tasks. The computation of discord is mostly confined to two-qubit systems for which an analytical calculational scheme is available. The utilization of quantum correlations in quantum information-based applications is limited by the problem of decoherence, i.e., the loss of coherence due to the inevitable interaction of a quantum system with its environment. The dynamics of quantum correlations due to decoherence may be studied in the Kraus operator formalism for different types of quantum channels representing system-environment interactions. In this review, we describe the salient features of the dynamics of classical and quantum correlations in a two-qubit system under Markovian (memoryless) time evolution. The two-qubit state considered is described by the reduced density matrix obtained from the ground state of a spin model. The models considered include the transverse-field XY model in one dimension, a special case of which is the transverse-field Ising model, and the XXZ spin chain. The quantum channels studied include the amplitude damping, bit-flip, bit-phase-flip and phase-flip channels. The Kraus operator formalism is briefly introduced and the origins of different types of dynamics discussed. One can identify appropriate quantities associated with the dynamics of quantum correlations which provide signatures of quantum phase transitions in the spin models. Experimental observations of the different types of dynamics are also mentioned.

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12

Baugh, J., J. S. Fung, J. Mracek e R. R. LaPierre. "Building a spin quantum bit register using semiconductor nanowires". Nanotechnology 21, n. 13 (8 marzo 2010): 134018. http://dx.doi.org/10.1088/0957-4484/21/13/134018.

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13

Al-Bustami, H., B. P. Bloom, Amir Ziv, S. Goldring, S. Yochelis, R. Naaman, D. H. Waldeck e Y. Paltiel. "Optical Multilevel Spin Bit Device Using Chiral Quantum Dots". Nano Letters 20, n. 12 (13 novembre 2020): 8675–81. http://dx.doi.org/10.1021/acs.nanolett.0c03445.

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14

WU, C. Q., Z. B. SU e L. YU. "SCHWINGER-BOSON STUDIES OF THE SINGLE HOLE MOTION IN A 2D QUANTUM ANTIFERROMAGNET". International Journal of Modern Physics B 08, n. 27 (15 dicembre 1994): 3843–58. http://dx.doi.org/10.1142/s0217979294001652.

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Within the Schwinger-boson approach for the t-J model, the single hole problem in a two-dimensional quantum antiferromagnet is studied by using the quantum Bogoliubovde Gennes formalism which treats the distortion of the spin background and quantum spin fluctuations on an equal footing. Several self-trapped localized hole states are found in the distorted spin-background as in the case of an anisotropic Heisenberg model. These localized hole states survive at finite temperatures when the antiferromagnetic order becomes short-ranged. The energy separation between the two lowest states is reduced by considering the spin-background distortion, but it remains finite.

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15

Su, Z. B., Y. M. Li, W. Y. Lai e L. Yu. "Self-Consistent Hole Motion and Spin Excitations in A Quantum Antiferromagnet". International Journal of Modern Physics B 03, n. 12 (dicembre 1989): 1913–32. http://dx.doi.org/10.1142/s021797928900124x.

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A new quantum Bogoliubov-de Gennes (BdeG) formalism is developed to study the self-consistent motion of holes and spin excitations in a quantum antiferromagnet within the generalized t-J model. On the one hand, the effects of local distortion of spin configurations and the renormalization of the hole motion due to virtual excitations of the distorted spin background are treated on an equal footing to obtain the hole wave function and its spectrum, as well as the effective mass for a propagating hole. On the other hand, the change of the spin excitation spectrum and the spin correlations due to the presence of dynamical holes are studied within the same adiabatic approximation. The stability of the hole states with respect to such changes justifies the self-consistency of the proposed formalism.

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16

Simmons, Stephanie, Hua Wu e John J. L. Morton. "Controlling and exploiting phases in multi-spin systems using electron spin resonance and nuclear magnetic resonance". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 370, n. 1976 (13 ottobre 2012): 4794–809. http://dx.doi.org/10.1098/rsta.2011.0354.

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The phase of a superposition state is a quintessential characteristic that differentiates a quantum bit of information from a classical one. This phase can be manipulated dynamically or geometrically, and can be exploited to sensitively estimate Hamiltonian parameters, perform faithful quantum state tomography and encode quantum information into multiple modes of an ensemble. Here we discuss the methods that we have employed to manipulate and exploit the phase information of single-, two-, multi-qubit and multi-mode spin systems.

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SHRIVASTAVA, KESHAV N. "PARTICLE–HOLE SYMMETRY IN QUANTUM HALL EFFECT". Modern Physics Letters B 13, n. 29n30 (30 dicembre 1999): 1087–90. http://dx.doi.org/10.1142/s0217984999001342.

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18

TESIO, ENRICO, STEFANO OLIVARES e MATTEO G. A. PARIS. "OPTIMIZED QUBIT PHASE ESTIMATION IN NOISY QUANTUM CHANNELS". International Journal of Quantum Information 09, supp01 (gennaio 2011): 379–87. http://dx.doi.org/10.1142/s0219749911007356.

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We address the estimation of phase-shifts for qubit systems in the presence of noise. Different sources of noise are considered including bit flip, bit-phase flip and phase flip. We derive the ultimate quantum limits to precision of estimation by evaluating the analytical expressions of the quantum Fisher information and assess performances of feasible measurements by evaluating the Fisher information for realistic spin-like measurements. We also propose an experimental scheme to test our results.

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19

Amiri, Manouchehr. "A Physical Theory of Information Vs. A Mathematical Theory of Communication". International Journal of Information Sciences and Techniques 13, n. 3 (27 maggio 2023): 01–10. http://dx.doi.org/10.5121/ijist.2023.13301.

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This article introduces a general notion of physical bit information that is compatible with the basics of quantum mechanics and incorporates the Shannon entropy as a special case. This notion of physical information leads to the Binary data matrix model (BDM), which predicts the basic results of quantum mechanics, general relativity, and black hole thermodynamics. The compatibility of the model with holographic, information conservation, and Landauer’s principle are investigated. After deriving the “Bit Information principle” as a consequence of BDM, the fundamental equations of Planck, De Broglie, Bekenstein, and mass-energy equivalence are derived.

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20

Climente, J. I., C. Segarra e J. Planelles. "Spin–orbit-induced hole spin relaxation in InAs and GaAs quantum dots". New Journal of Physics 15, n. 9 (5 settembre 2013): 093009. http://dx.doi.org/10.1088/1367-2630/15/9/093009.

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21

Ares, N., G. Katsaros, V. N. Golovach, J. J. Zhang, A. Prager, L. I. Glazman, O. G. Schmidt e S. De Franceschi. "SiGe quantum dots for fast hole spin Rabi oscillations". Applied Physics Letters 103, n. 26 (23 dicembre 2013): 263113. http://dx.doi.org/10.1063/1.4858959.

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22

Baylac, B., T. Amand, X. Marie, B. Dareys, M. Brousseau, G. Bacquet e V. Thierry-Mieg. "Hole spin relaxation in n-modulation doped quantum wells". Solid State Communications 93, n. 1 (gennaio 1995): 57–60. http://dx.doi.org/10.1016/0038-1098(94)00721-7.

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23

Gündoğdu, K., K. C. Hall, E. J. Koerperick, C. E. Pryor, M. E. Flatté, Thomas F. Boggess, O. B. Shchekin e D. G. Deppe. "Electron and hole spin dynamics in semiconductor quantum dots". Applied Physics Letters 86, n. 11 (14 marzo 2005): 113111. http://dx.doi.org/10.1063/1.1857067.

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Segarra, C., J. I. Climente, F. Rajadell e J. Planelles. "Hole spin relaxation in InAs/GaAs quantum dot molecules". Journal of Physics: Condensed Matter 27, n. 41 (29 settembre 2015): 415301. http://dx.doi.org/10.1088/0953-8984/27/41/415301.

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25

Barrau, J., G. Bacquet, F. Hassen, N. Lauret, T. Amand e M. Brousseau. "Luminescence polarization and hole spin-relaxation in quantum wells". Superlattices and Microstructures 14, n. 1 (luglio 1993): 27. http://dx.doi.org/10.1006/spmi.1993.1099.

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26

Dinu, I. V., V. Moldoveanu, R. Dragomir e B. Tanatar. "Unpinning of heavy hole spin in magnetic quantum dots". physica status solidi (b) 254, n. 5 (27 dicembre 2016): 1600800. http://dx.doi.org/10.1002/pssb.201600800.

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Paik, Biplab. "Test of indestructibility of a nonsingular black hole". International Journal of Modern Physics D 26, n. 14 (dicembre 2017): 1750165. http://dx.doi.org/10.1142/s0218271817501656.

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Classical singular black holes are known to obey the cosmic censorship conjecture, and therefore are indestructible until they get completely evaporated by the Hawking radiation phenomenon. However, a nonsingular quantum black hole may not be necessarily indestructible. To proceed in this test, we deduce the first law of thermodynamics for the renormalization technique based, quantum improved, nonsingular Kerr class black hole, and then the test is done by Wald’s method. It emerges that while the quantum improvement leads to an escape for black hole from complete evaporation, it also makes a spinning black hole well destructible against overspinning. Even though, in general, spinning quantum black holes appear quite destructible, in the regime of exceedingly low rate of allowed spin, slower the spin becomes, weaker happens to be the probability of black hole getting destroyed. In particular, the minimally energized black hole relic, which is of a Schwarzschild class, emerges absolutely indestructible. It has further been argued that the practical stable existence of “G-lumps” is improbable. In context of our formal work, we find a great scope for figuring out the quantum corrected differential version of “entropy-area law” for Kerr class black hole.

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Roussignol, Ph, P. Rolland, R. Ferreira, C. Delalande, G. Bastard, A. Vinattieri, J. Martinez-Pastor et al. "Hole polarization and slow hole-spin relaxation in ann-doped quantum-well structure". Physical Review B 46, n. 11 (15 settembre 1992): 7292–95. http://dx.doi.org/10.1103/physrevb.46.7292.

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KAMENEV, D. I., G. P. BERMAN, R. B. KASSMAN e V. I. TSIFRINOVICH. "MODELING FULL ADDER IN ISING SPIN QUANTUM COMPUTER WITH 1000 QUBITS USING QUANTUM MAPS". International Journal of Quantum Information 02, n. 03 (settembre 2004): 323–40. http://dx.doi.org/10.1142/s0219749904000304.

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The quantum adder is an essential attribute of a quantum computer, just as classical adder is needed for operation of a digital computer. We model the quantum full adder as a realistic complex algorithm on a large number of qubits in an Ising spin quantum computer. Our results are an important step toward effective modeling of the quantum modular adder which is needed for Shor's and other quantum algorithms. Our full adder has the following features. (i) The near-resonant transitions with small detunings are completely suppressed, which allows us to decrease errors by several orders of magnitude and to model a 1000-qubit full adder. (We add a 1000-bit number using 2001 spins.) (ii) We construct the full adder gates directly as sequences of radio-frequency pulses, rather than breaking them down into generalized logical gates, such as Control-Not and one qubit gates. This substantially reduces the number of pulses needed to implement the full adder. (The maximum number of pulses required to add one bit (F-gate) is 15.) (iii) Full adder is realized in a homogeneous spin chain. (iv) The phase error is minimized: the F-gates generate approximately the same phase for different states of the superposition. (v) Modeling of the full adder is performed using quantum maps instead of differential equations. This allows us to reduce the calculation time to a reasonable value.

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Mukesh, Nain, Bence G. Márkus, Nikoletta Jegenyes, Gábor Bortel, Sarah M. Bezerra, Ferenc Simon, David Beke e Adam Gali. "Formation of Paramagnetic Defects in the Synthesis of Silicon Carbide". Micromachines 14, n. 8 (28 luglio 2023): 1517. http://dx.doi.org/10.3390/mi14081517.

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Silicon carbide (SiC) is a very promising platform for quantum information processing, as it can host room temperature solid state defect quantum bits. These room temperature quantum bits are realized by paramagnetic silicon vacancy and divacancy defects in SiC that are typically introduced by irradiation techniques. However, irradiation techniques often introduce unwanted defects near the target quantum bit defects that can be detrimental for the operation of quantum bits. Here, we demonstrate that by adding aluminum precursor to the silicon and carbon sources, quantum bit defects are created in the synthesis of SiC without any post treatments. We optimized the synthesis parameters to maximize the paramagnetic defect concentrations—including already established defect quantum bits—monitored by electron spin resonance spectroscopy.

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JABERI, M., H. RAHIMPOUR SOLEIMANI e A. H. FARAHBOD. "EFFECT OF THE ELECTRON SPIN-RELAXATION ON OPTICAL BISTABILITY VIA THE HEAVY-HOLE AND THE LIGHT-HOLE". Modern Physics Letters B 28, n. 04 (4 febbraio 2014): 1450027. http://dx.doi.org/10.1142/s0217984914500274.

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In this paper, the influence of the spin-relaxation on the optical bistability via a nonradiative coherence between the heavy-hole and the light-hole in a GaAs quantum well inside a unidirectional ring cavity is studied. In the present theoretical model, spin-relaxation was considered as a source for decoherence and it was found that the spin-relaxation leads to the change of optical bistability behavior, including increase in threshold intensity and hysteresis loop. Furthermore, in the presence of spin-relaxation, the transition from optical bistability to optical multistability can be obtained by tuning the applied field.

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Vasan, R., H. Salman e M. O. Manasreh. "All inorganic quantum dot light emitting devices with solution processed metal oxide transport layers". MRS Advances 1, n. 4 (2016): 305–10. http://dx.doi.org/10.1557/adv.2016.129.

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ABSTRACTAll inorganic quantum dot light emitting devices with solution processed transport layers are investigated. The device consists of an anode, a hole transport layer, a quantum dot emissive layer, an electron transport layer and a cathode. Indium tin oxide coated glass slides are used as substrates with the indium tin oxide acting as the transparent anode electrode. The transport layers are both inorganic, which are relatively insensitive to moisture and other environmental factors as compared to their organic counterparts. Nickel oxide acts as the hole transport layer, while zinc oxide nanocrystals act as the electron transport layer. The nickel oxide hole transport layer is formed by annealing a spin coated layer of nickel hydroxide sol-gel. On top of the hole transport layer, CdSe/ZnS quantum dots synthesized by hot injection method is spin coated. Finally, zinc oxide nanocrystals, dispersed in methanol, are spin coated over the quantum dot emissive layer as the electron transport layer. The material characterization of different layers is performed by using absorbance, Raman scattering, XRD, and photoluminescence measurements. The completed device performance is evaluated by measuring the IV characteristics, electroluminescence and quantum efficiency measurements. The device turn on is around 4V with a maximum current density of ∼200 mA/cm2 at 9 V.

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Punk, Matthias, Andrea Allais e Subir Sachdev. "Quantum dimer model for the pseudogap metal". Proceedings of the National Academy of Sciences 112, n. 31 (20 luglio 2015): 9552–57. http://dx.doi.org/10.1073/pnas.1512206112.

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We propose a quantum dimer model for the metallic state of the hole-doped cuprates at low hole density, p. The Hilbert space is spanned by spinless, neutral, bosonic dimers and spin S=1/2, charge +e fermionic dimers. The model realizes a “fractionalized Fermi liquid” with no symmetry breaking and small hole pocket Fermi surfaces enclosing a total area determined by p. Exact diagonalization, on lattices of sizes up to 8×8, shows anisotropic quasiparticle residue around the pocket Fermi surfaces. We discuss the relationship to experiments.

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34

Chibisov, Andrey, Maxim Aleshin e Mary Chibisova. "DFT Analysis of Hole Qubits Spin State in Germanium Thin Layer". Nanomaterials 12, n. 13 (29 giugno 2022): 2244. http://dx.doi.org/10.3390/nano12132244.

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Due to the presence of a strong spin–orbit interaction, hole qubits in germanium are increasingly being considered as candidates for quantum computing. These objects make it possible to create electrically controlled logic gates with the basic properties of scalability, a reasonable quantum error correction, and the necessary speed of operation. In this paper, using the methods of quantum-mechanical calculations and considering the non-collinear magnetic interactions, the quantum states of the system 2D structure of Ge in the presence of even and odd numbers of holes were investigated. The spatial localizations of hole states were calculated, favorable quantum states were revealed, and the magnetic structural characteristics of the system were analyzed.

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35

RP, Vyas. "Implications of New Quantum Spin Perspective in Quantum Gravity". Physical Science & Biophysics Journal 7, n. 1 (5 gennaio 2023): 1–10. http://dx.doi.org/10.23880/psbj-16000235.

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Consequences of new quantum spin perspective in quantum gravity are far-reaching. Results of this novel perspective in loop quantum gravity, i.e., the modification of the equation of geometrical operators such as the area and the volume operator are known. Using newly proposed formula from this perspective, the magnitude of fundamental constants such as the reduced Planck constant ℏ, the gravitational constant G, the speed of light c, the Boltzmann constant kβ , the fine structure constant α, can be validated. With the aid of this perspective, we find new formulas for the fundamental Planckian quantities and the derived Planckian quantities. We also propose novel formulas for the Planck star such as the size, the curvature, the surface area and the size of black hole (for the Planck star) without modifying its significance. The relation of the quantum spin with the Planck temperature TP (TP ∝ n2 ), the Planck mass mP (mP ∝ n2 ), the Planck length l P (l P ∝ n) are also proposed using this novel perspective.

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36

SOUMA, SATOFUMI, SEUNG JOO LEE e TAE WON KANG. "NUMERICAL STUDY OF FERROMAGNETISM IN DILUTED MAGNETIC SEMICONDUCTOR QUANTUM-WELLS". International Journal of Modern Physics B 19, n. 19 (30 luglio 2005): 3151–60. http://dx.doi.org/10.1142/s0217979205031973.

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We study the ferromagnetism in III-V diluted magnetic semiconductor (DMS) quantum-wells theoretically and numerically taking into account the occupation of multiple subbands by holes in quantum wells. Starting from the mean-field theory of carrier-induced ferromagnetism in III-V DMS along with the exchange-correlation interaction of holes within the local spin density approximation, we found that the ferromagnetic transition temperature Tc of DMS quantum-wells exhibits step-function-like dependence on the hole density, reflecting the quasi-two-dimensional nature of systems. Moreover, the temperature dependence of the spin polarization shows quite distinct characteristics depending on the hole density.

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37

Lafont, Fabien, Amir Rosenblatt, Moty Heiblum e Vladimir Umansky. "Counter-propagating charge transport in the quantum Hall effect regime". Science 363, n. 6422 (3 gennaio 2019): 54–57. http://dx.doi.org/10.1126/science.aar3766.

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The quantum Hall effect, observed in a two-dimensional (2D) electron gas subjected to a perpendicular magnetic field, imposes a 1D-like chiral, downstream, transport of charge carriers along the sample edges. Although this picture remains valid for electrons and Laughlin’s fractional quasiparticles, it no longer holds for quasiparticles in the so-called hole-conjugate states. These states are expected, when disorder and interactions are weak, to harbor upstream charge modes. However, so far, charge currents were observed to flow exclusively downstream in the quantum Hall regime. Studying the canonical spin-polarized and spin-unpolarized v = 2/3 hole-like states in GaAs-AlGaAs heterostructures, we observed a significant upstream charge current at short propagation distances in the spin unpolarized state.

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38

Xu, Gang, Fei Gao, Ke Wang, Ting Zhang, He Liu, Gang Cao, Ting Wang et al. "Hole spin in tunable Ge hut wire double quantum dot". Applied Physics Express 13, n. 6 (7 maggio 2020): 065002. http://dx.doi.org/10.35848/1882-0786/ab8b6d.

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39

Rajadell, F., J. I. Climente e J. Planelles. "Large hole spin anticrossings in InAs/GaAs double quantum dots". Applied Physics Letters 103, n. 13 (23 settembre 2013): 132105. http://dx.doi.org/10.1063/1.4823458.

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40

Yokoo, T., S. Itoh, S. Ibuka, H. Yoshizawa e J. Akimitsu. "Spin and Hole Dynamics in Carrier-Doped Quantum Haldane Chain". Journal of Physics: Conference Series 568, n. 4 (8 dicembre 2014): 042035. http://dx.doi.org/10.1088/1742-6596/568/4/042035.

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41

Roussignol, Ph, R. Ferreira, C. Delalande, G. Bastard, A. Vinattieri, J. Martinez-Pastor, L. Carraresi, M. Colocci, J. F. Palmier e B. Etienne. "Hole spin relaxation in a n-doped quantum well structure". Surface Science 305, n. 1-3 (marzo 1994): 263–66. http://dx.doi.org/10.1016/0039-6028(94)90897-4.

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42

Amand, T., B. Dareys, B. Baylac, X. Marie, J. Barrau, M. Brousseau, D. J. Dunstan e R. Planel. "Exciton formation and hole-spin relaxation in intrinsic quantum wells". Physical Review B 50, n. 16 (15 ottobre 1994): 11624–28. http://dx.doi.org/10.1103/physrevb.50.11624.

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43

Nayak, M. G., e L. K. Saini. "Spin-Polarized Symmetric Electron-Hole Quantum Bilayers: Finite width Effect". Contributions to Plasma Physics 52, n. 3 (aprile 2012): 211–18. http://dx.doi.org/10.1002/ctpp.201100045.

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44

Babar, R., W. Javed e A. Övgün. "Effect of the GUP on the Hawking radiation of black hole in 2 + 1 dimensions with quintessence and charged BTZ-like magnetic black hole". Modern Physics Letters A 35, n. 13 (27 febbraio 2020): 2050104. http://dx.doi.org/10.1142/s0217732320501047.

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In this paper, we investigate the Hawking radiation process by using the quantum tunneling phenomenon of massive spin-1 (W-bosons) and spin-0 particles by the black hole in 2 + 1 dimensions surrounded by quintessence as well as charged BTZ-like magnetic black hole. First of all, by using Hamilton–Jacobi ansatz and WKB approximation to the field equation of massive vector particles, we get the required tunneling rate of emitted particles and obtain the corresponding Hawking temperature [Formula: see text] for the black hole (BH) surrounded by quintessence. In order to study the quantum gravity effects, we utilize the generalized Proca and Klein–Gordan equations incorporating the generalized uncertainty principle (GUP) for these BHs and recover their modified tunneling probability as well as accompanying quantum corrected temperatures [Formula: see text].

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45

Yakovlev, D. R., D. H. Feng, V. V. Pavlov, A. V. Rodina, E. V. Shornikova, J. Mund e M. Bayer. "Photocharging dynamics in colloidal CdS quantum dots visualized by electron spin coherence". Физика и техника полупроводников 52, n. 4 (2018): 489. http://dx.doi.org/10.21883/ftp.2018.04.45838.27.

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AbstractWe use a time-resolved technique with three laser pulses (pump, orientation and probe) to study the photocharging dynamics with picosecond resolution on a long timescale ranging from ps to ms in CdS colloidal quantum dots. The detection is based on measuring the coherent spin dynamics of electrons, allowing us to distinguish the type of carrier in the dot core (electron or hole). We find that although initially negative photocharging happens because of fast hole trapping on surface states, eventually it evolves to positive photocharging due to electron trapping and hole detrapping. The positive photocharging lasts up to hundreds of microseconds at room temperature.

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46

Liu, Yang, Shan Guan, Jun‐Wei Luo e Shu‐Shen Li. "Progress of Gate‐Defined Semiconductor Spin Qubit: Host Materials and Device Geometries". Advanced Functional Materials, 10 gennaio 2024. http://dx.doi.org/10.1002/adfm.202304725.

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AbstractQuantum computing offers the potential to revolutionize information processing by exploiting the principles of quantum mechanics. Among the diverse quantum bit (qubit) technologies, silicon‐based semiconductor spin qubits have emerged as a promising contender due to their potential scalability and compatibility with existing semiconductor technologies. In this paper, the latest developments of spin qubits in gate‐defined semiconducting nanostructures made of silicon and germanium, starting from the basic properties of electron and hole states in group‐IV semiconductors, are reviewed. Specifically, various nanostructures that exploit their unique microscopic properties for qubit implementations, elaborating on the advances and challenges in experiments, are discussed. Strategies for enhancing qubit performance, such as designing new nanostructures and identifying suitable operating points, particularly those involving the valleys of electron qubits and the heavy‐hole–light‐hole mixing of hole qubits, are also highlighted. This comprehensive review thus provides valuable insights into the current state‐of‐the‐art in semiconductor quantum computing and suggests avenues for future research.

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47

Sacksteder, Vincent E., e B. Andrei Bernevig. "Hole spin helix: Anomalous spin diffusion in anisotropic strained hole quantum wells". Physical Review B 89, n. 16 (29 aprile 2014). http://dx.doi.org/10.1103/physrevb.89.161307.

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48

Woods, L. M., T. L. Reinecke e R. Kotlyar. "Hole spin relaxation in quantum dots". Physical Review B 69, n. 12 (22 marzo 2004). http://dx.doi.org/10.1103/physrevb.69.125330.

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49

Zhao Yan-Jun, Tan Ning, Wang Yu-Qi, Zheng Ya-Rui, Wang Hui e Liu Wu-Ming. "Quantum state transport in square lattice superconducting qubit circuits under gauge potential". Acta Physica Sinica, 2023, 0. http://dx.doi.org/10.7498/aps.72.20222349.

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In this paper, we study the transport properties of quantum states in the square transport quantum bit model by using an inductive coupler to generate an artificial gauge potential (effective magnetic flux) It is found by theoretical calculation that the eigenstates of single particle and single hole have the same eigen energy spectrum, and the average particle flow and average hole flow of the two are opposite to each other under the sine modulation of effective magnetic flux under the same energy When the initial state is a single particle and a single hole occupying a lattice, if the system time inversion is symmetric (the effective magnetic flux is an integral multiple of 4<i>π</i>), the components of the time-dependent wave functions of the single particle and the single hole are equal, otherwise they are not equal The analysis proves that the above calculation results are due to the fact that the particle hole operation for the Hamiltonian of the system is equivalent to the time inversion In addition, it is found that when the effective magnetic flux is <i>π</i>, a single particle or a single hole is only transported between the initial bit and two adjacent bits, and when the effective magnetic flux is 0, a single particle or a single hole is transported to the diagonal bit through two adjacent bits, and then transported in reverse; Regardless of the value of effective magnetic flux, both have the same average (particle or hole) current and lattice occupation probability.

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50

Eble, Benoit, Christophe Testelin, Pascal Desfonds, Frederic Bernardot, Andrea Balocchi, Thierry Amand, Anne Miard, Aristide Lemaître, Xavier Marie e Maria Chamarro. "Experimental Evidence of the Hyperfine Interaction between Hole and Nuclear Spins in InAs/GaAs Quantum Dots". MRS Proceedings 1183 (2009). http://dx.doi.org/10.1557/proc-1183-ff05-01.

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AbstractThe spin dynamics of resident holes in singly p-doped InAs/GaAs quantum dots is studied by pump-probe photo-induced circular dichroism experiments. We show that the hole spin dephasing is controlled by the hyperfine interaction between the hole spin and nuclear spins. We find a characteristic hole spin dephasing time of 12 ns, in close agreement with our calculations based on a dipole-dipole coupling between the hole and the quantum dot nuclei. Finally we demonstrate that a small external magnetic field, typically 10 mT, quenches the hyperfine hole spin dephasing.

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