Relevant bibliographies by topics / Transman qubit

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  1. Journal articles
  2. Dissertations / Theses
  3. Book chapters
  4. Conference papers

Academic literature on the topic 'Transman qubit'

Author: Grafiati
Published: 6 September 2023

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Journal articles on the topic "Transman qubit"

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Said, T., A. Chouikh, K. Essammouni, and M. Bennai. "Implementing N-quantum phase gate via circuit QED with qubit–qubit interaction." Modern Physics Letters B 30, no. 05 (February 20, 2016): 1650050. http://dx.doi.org/10.1142/s0217984916500500.

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We propose a method for realizing a quantum phase gate of one qubit simultaneously controlling [Formula: see text] target qubits based on the qubit–qubit interaction. We show how to implement the proposed gate with one transmon qubit simultaneously controlling [Formula: see text] transmon qubits in a circuit QED driven by a strong microwave field. In our scheme, the operation time of this phase gate is independent of the number [Formula: see text] of qubits. On the other hand, this gate can be realized in a time of nanosecond-scale much smaller than the decoherence time and dephasing time both being the time of microsecond-scale. Numerical simulation of the occupation probabilities of the second excited lever shows that the scheme could be achieved efficiently within current technology.
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Yuan, Wei-Ping, Zhi-Cheng He, Sai Li, and Zheng-Yuan Xue. "Fast Reset Protocol for Superconducting Transmon Qubits." Applied Sciences 13, no. 2 (January 6, 2023): 817. http://dx.doi.org/10.3390/app13020817.

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For larger-scale quantum information processing, qubit reset plays an important role, as the coherent times for qubits are limited. However, previous schemes require either long reset times or a complex pulse calibration technique, leading to low efficiency in qubit reset. Here, we propose a fast and simple reset protocol for superconducting transmon qubits based on the coupler-coupled qubits architecture. In this setup, a mixing pulse is used to transfer the qubit excitation to the combined excitation of a low-qulity coupler and readout resonator, which will quickly decay to their respectively ground states, leading to efficient qubit reset to the ground state. Our numerical results show that the residual population of the qubit’s excited state can be suppressed to 0.04% within 28 ns; the reset time will be 283 ns if photon depletion of the readout resonator is required. Thus, our protocol provides a promising way for the high-efficiency superconducting qubit reset.
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Sun, Xiaopei, Bing Li, Enna Zhuo, Zhaozheng Lyu, Zhongqing Ji, Jie Fan, Xiaohui Song, et al. "Realization of superconducting transmon qubits based on topological insulator nanowires." Applied Physics Letters 122, no. 15 (April 10, 2023): 154001. http://dx.doi.org/10.1063/5.0140079.

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Topological-material-based Josephson junctions have the potential to be used to host Majorana zero modes and to construct topological qubits. For operating the topological qubits at an appropriate timescale to avoid decoherence and quasiparticle poisoning, one would eventually go to the time domain and embed the topological qubits into quantum electrodynamic circuits. Here, we constructed a topological-insulator-nanowire-based transmon qubit and demonstrated its strong coupling to a coplanar waveguide resonator. The flux-tunable spectrum and Rabi oscillations with a qubit lifetime [Formula: see text] of [Formula: see text] were observed. Such a hybrid platform, containing topological materials and quantum electrodynamic circuits, can further be used to study the physical properties such as Majorana zero modes in topological quantum circuits.
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Tao, Rui, Xiao-Tao Mo, Zheng-Yuan Xue, and Jian Zhou. "Practical one-step synthesis of multipartite entangled states on superconducting circuits." International Journal of Quantum Information 17, no. 07 (October 2019): 1950051. http://dx.doi.org/10.1142/s0219749919500515.

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Quantum entanglement is an important resource for quantum information processing tasks. However, realistic multipartite entangled state production is very difficult. In this paper, we propose an efficient single-step scheme for generating many body Greenberger–Horne–Zeilinger (GHZ) states on superconducting circuits by using a superconducting transmission-line resonator (TLR) interact with [Formula: see text] superconducting transmon qubits. The distinct merit of our proposal is that it does not require the qubit-resonator coupling strengths to be the same, which is usually impractical experimentally, and thus is one of the main reasons for entanglement generation infidelity in previous single-step schemes. The removing of the uniform interaction requirement is achieved by modulating the qubits splitting frequencies with ac microwave fields, which results in tunable individual qubit-resonator coupling strength, and thus effective uniform qubit–qubit interaction Hamiltonian can be obtained. Since microwave control is conventional nowadays, our proposal can be directly tested experimentally, which makes previous multipartite entangled states generation schemes more efficient.
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Kubo, Kentaro, and Hayato Goto. "Fast parametric two-qubit gate for highly detuned fixed-frequency superconducting qubits using a double-transmon coupler." Applied Physics Letters 122, no. 6 (February 6, 2023): 064001. http://dx.doi.org/10.1063/5.0138699.

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High-performance two-qubit gates have been reported with superconducting qubits coupled via a single-transmon coupler (STC). Most of them are implemented for qubits with a small detuning since reducing residual ZZ coupling for highly detuned qubits by an STC is challenging. In terms of the frequency crowding and crosstalk, however, highly detuned qubits are desirable. Here, we numerically demonstrate a high-performance parametric gate for highly detuned fixed-frequency qubits using a recently proposed tunable coupler called a double-transmon coupler (DTC). Applying an ac flux pulse, we can perform a maximally entangling universal gate ([Formula: see text]) with an average fidelity over 99.99% and a short gate time of about 24 ns. This speed is comparable to resonance-based gates for slightly detuned tunable qubits. Moreover, using a dc flux pulse alternatively, we can achieve another kind of entangling gate called a CZ gate with an average fidelity over 99.99% and a gate time of about 18 ns. Given the flexibility and feasible settings, we can expect that the DTC will contribute towards realizing a high-performance quantum computer in the near future.
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Dong, Yuqian, Yong Li, Wen Zheng, Yu Zhang, Zhuang Ma, Xinsheng Tan, and Yang Yu. "Measurement of Quasiparticle Diffusion in a Superconducting Transmon Qubit." Applied Sciences 12, no. 17 (August 24, 2022): 8461. http://dx.doi.org/10.3390/app12178461.

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Quasiparticles, especially the ones near the Josephson junctions in the superconducting qubits, are known as an important source of decoherence. By injecting quasiparticles into a quantum chip, we characterized the diffusion feature by measuring the energy relaxation time and the residual excited-state population of a transmon qubit. From the extracted transition rates, we phenomenologically modeled the quasiparticle diffusion in a superconducting circuit that contained “hot” nonequilibrium quasiparticles in addition to low-energy ones.
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Ye, Yangsen, Sirui Cao, Yulin Wu, Xiawei Chen, Qingling Zhu, Shaowei Li, Fusheng Chen, et al. "Realization of High-Fidelity Controlled-Phase Gates in Extensible Superconducting Qubits Design with a Tunable Coupler." Chinese Physics Letters 38, no. 10 (November 1, 2021): 100301. http://dx.doi.org/10.1088/0256-307x/38/10/100301.

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High-fidelity two-qubit gates are essential for the realization of large-scale quantum computation and simulation. Tunable coupler design is used to reduce the problem of parasitic coupling and frequency crowding in many-qubit systems and thus thought to be advantageous. Here we design an extensible 5-qubit system in which center transmon qubit can couple to every four near-neighboring qubits via a capacitive tunable coupler and experimentally demonstrate high-fidelity controlled-phase (CZ) gate by manipulating central qubit and one near-neighboring qubit. Speckle purity benchmarking and cross entropy benchmarking are used to assess the purity fidelity and the fidelity of the CZ gate. The average purity fidelity of the CZ gate is 99.69±0.04% and the average fidelity of the CZ gate is 99.65±0.04%, which means that the control error is about 0.04%. Our work is helpful for resolving many challenges in implementation of large-scale quantum systems.
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Bultink, C. C., T. E. O’Brien, R. Vollmer, N. Muthusubramanian, M. W. Beekman, M. A. Rol, X. Fu, et al. "Protecting quantum entanglement from leakage and qubit errors via repetitive parity measurements." Science Advances 6, no. 12 (March 2020): eaay3050. http://dx.doi.org/10.1126/sciadv.aay3050.

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Protecting quantum information from errors is essential for large-scale quantum computation. Quantum error correction (QEC) encodes information in entangled states of many qubits and performs parity measurements to identify errors without destroying the encoded information. However, traditional QEC cannot handle leakage from the qubit computational space. Leakage affects leading experimental platforms, based on trapped ions and superconducting circuits, which use effective qubits within many-level physical systems. We investigate how two-transmon entangled states evolve under repeated parity measurements and demonstrate the use of hidden Markov models to detect leakage using only the record of parity measurement outcomes required for QEC. We show the stabilization of Bell states over up to 26 parity measurements by mitigating leakage using postselection and correcting qubit errors using Pauli-frame transformations. Our leakage identification method is computationally efficient and thus compatible with real-time leakage tracking and correction in larger quantum processors.
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Groszkowski, Peter, and Jens Koch. "Scqubits: a Python package for superconducting qubits." Quantum 5 (November 17, 2021): 583. http://dx.doi.org/10.22331/q-2021-11-17-583.

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scqubits is an open-source Python package for simulating and analyzing superconducting circuits. It provides convenient routines to obtain energy spectra of common superconducting qubits, such as the transmon, fluxonium, flux, cos(2ϕ) and the 0-π qubit. scqubits also features a number of options for visualizing the computed spectral data, including plots of energy levels as a function of external parameters, display of matrix elements of various operators as well as means to easily plot qubit wavefunctions. Many of these tools are not limited to single qubits, but extend to composite Hilbert spaces consisting of coupled superconducting qubits and harmonic (or weakly anharmonic) modes. The library provides an extensive suite of methods for estimating qubit coherence times due to a variety of commonly considered noise channels. While all functionality of scqubits can be accessed programatically, the package also implements GUI-like widgets that, with a few clicks can help users both create relevant Python objects, as well as explore their properties through various plots. When applicable, the library harnesses the computing power of multiple cores via multiprocessing. scqubits further exposes a direct interface to the Quantum Toolbox in Python (QuTiP) package, allowing the user to efficiently leverage QuTiP's proven capabilities for simulating time evolution.
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Ahmad, Halima Giovanna, Caleb Jordan, Roald van den Boogaart, Daan Waardenburg, Christos Zachariadis, Pasquale Mastrovito, Asen Lyubenov Georgiev, et al. "Investigating the Individual Performances of Coupled Superconducting Transmon Qubits." Condensed Matter 8, no. 1 (March 21, 2023): 29. http://dx.doi.org/10.3390/condmat8010029.

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The strong requirement for high-performing quantum computing led to intensive research on novel quantum platforms in the last decades. The circuital nature of Josephson-based quantum superconducting systems powerfully supports massive circuital freedom, which allowed for the implementation of a wide range of qubit designs, and an easy interface with the quantum processing unit. However, this unavoidably introduces a coupling with the environment, and thus to extra decoherence sources. Moreover, at the time of writing, control and readout protocols mainly use analogue microwave electronics, which limit the otherwise reasonable scalability in superconducting quantum circuits. Within the future perspective to improve scalability by integrating novel control energy-efficient superconducting electronics at the quantum stage in a multi-chip module, we report on an all-microwave characterization of a planar two-transmon qubits device, which involves state-of-the-art control pulses optimization. We demonstrate that the single-qubit average gate fidelity is mainly limited by the gate pulse duration and the quality of the optimization, and thus does not preclude the integration in novel hybrid quantum-classical superconducting devices.
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Dissertations / Theses on the topic "Transman qubit"

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Bader, Samuel James. "Higher levels of the transmon qubit." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92701.

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Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 91-95).
This thesis discusses recent experimental work in measuring the properties of higher levels in transmon qubit systems. The first part includes a thorough overview of transmon devices, explaining the principles of the device design, the transmon Hamiltonian, and general Circuit Quantum Electrodynamics concepts and methodology. The second part discusses the experimental setup and methods employed in measuring the higher levels of these systems, and the details of the simulation used to explain and predict the properties of these levels.
by Samuel James Bader.
S.B.
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Convertini, Luciana. "Simulazione numerica di qubit a superconduttori di tipo transmon: dal layout al gate a singolo qubit." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022.

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In questo lavoro di tesi è stato messo a punto un insieme di modelli e strumenti di simulazione numerica che consentono nel loro insieme l’analisi completa di un sistema formato da qubit a superconduttore di tipo transmon per il calcolo quantistico. Appoggiandosi agli elementi noti della teoria del transmon, l’analisi parte dalla definizione del layout da cui, mediante simulazioni elettromagnetiche, si estraggono le matrici di capacità ed induttanza dei vari componenti. Questo consente la costruzione dell’Hamiltoniano del sistema, noto il quale si possono eseguire le simulazioni nel dominio del tempo delle operazioni dei vari gate, una volta definiti gli opportuni segnali di controllo. Per l’implementazione del flusso di simulazione si sono utilizzati sia strumenti software open-source (Qiskit Metal, FastCap, QuTip), sia script Python sviluppati allo scopo. A dimostrazione della funzionalità dell’ambiente così creato viene presentata l’analisi di un transmon accoppiato a risonatori e linee di trasmissione, tramite il quale si realizza un quantum gate a singolo qubit di tipo X.
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Andersson, Gustav. "Circuit quantum electrodynamics with a transmon qubit in a 3D cavity." Thesis, KTH, Tillämpad fysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-168010.

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Suri, Baladitya. "Transmon qubits coupled to superconducting lumped element resonators." Thesis, University of Maryland, College Park, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3711371.

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I discuss the design, fabrication and measurement at millikelvin-temperatures of Al/AlOx/Al Josephson junction-based transmon qubits coupled to superconducting thin-film lumped element microwave resonators made of aluminum on sapphire. The resonators had a center frequency of around 6GHz, and a total quality factor ranging from 15,000 to 70,000 for the various devices. The area of the transmon junctions was about 150 nm × 150 nm and with Josephson energy EJ such that 10GHz ≤ EJ ≤ 30 GHz. The charging energy of the transmons arising mostly from the large interdigital shunt capacitance, was Ec/h ≈ 300MHz.

I present microwave spectroscopy of the devices in the strongly dispersive regime of circuit quantum electrodynamics. In this limit the ac Stark shift due to a single photon in the resonator is greater than the linewidth of the qubit transition. When the resonator is driven coherently using a coupler tone, the transmon spectrum reveals individual "photon number'' peaks, each corresponding to a single additional photon in the resonator. Using a weighted average of the peak heights in the qubit spectrum, I calculated the average number of photons n¯ in the resonator. I also observed a nonlinear variation of n¯ with the applied power of the coupler tone Prf. I studied this nonlinearity using numerical simulations and found good qualitative agreement with data.

In the absence of a coherent drive on the resonator, a thermal population of 5.474 GHz photons in the resonator, at an effective temperature of 120 mK resulted in a weak n = 1 thermal photon peak in the qubit spectrum. In the presence of independent coupler and probe tones, the n = 1 thermal photon peak revealed an Autler-Townes splitting. The observed effect was explained accurately using the four lowest levels of the dispersively dressed Jaynes-Cummings transmon-resonator system, and numerical simulations of the steady-state master equation for the coupled system.

I also present time-domain measurements on transmons coupled to lumped-element resonators. From T1 and Rabi oscillation measurements, I found that my early transmon devices (called design LEv5) had lifetimes (T1 ∼ 1 μs) limited by strong coupling to the 50 Ω transmission line. This coupling was characterized by the the rate of change of the Rabi oscillation frequency with the change in the drive voltage (dfRabi /dV) – also termed the Rabi coupling to the drive. I studied the design of the transmon-resonator system using circuit analysis and microwave simulations with the aim being to reduce the Rabi coupling to the drive. By increasing the resonance frequency of the resonator ωr/2π from 5.4 GHz to 7.2 GHz, lowering the coupling of the resonator to the transmission line and thereby increasing the external quality factor Qe from 20,000 to 70,000, and reducing the transmon-resonator coupling g/2π from 70 MHz to 40 MHz, I reduced the Rabi coupling to the drive by an order of magnitude (∼ factor of 20). The T 1 ∼ 4 μs of devices in the new design (LEv6) was longer than that of the early devices, but still much shorter than the lifetimes predicted from Rabi coupling, suggesting the presence of alternative sources of noise causing qubit relaxation. Microwave simulations and circuit analysis in the presence of a dielectric loss tangent tan δ ≃ 5 × 10 -6 agree reasonably well with the measured T 1 values, suggesting that surface dielectric loss may be causing relaxation of transmons in the new designs.

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Schmitt, Vivien. "Design, fabrication and test of a four superconducting quantum-bit processor." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066184/document.

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Cette thèse présente le travail de conception, de fabrication et de test d'un processor à 4 qubits Josephson, avec un souci d’évolutivité. Les qubits ont une fréquence réglable et sont tous couplés à un unique bus de couplage, afin d’implémenter la porte à deux qubits iSWAP, sur n’importe quelle paire d'entre eux. Chaque qubit est aussi équipé d’un amplificateur Josephson à bifurcation (JBA). Le principe du processeur, le choix des paramètres, le design micro-onde ainsi que la fabrication sont décrits. Une première expérience montre la lecture simultanée, haute-fidélité et en un coup de tous les qubits, par une technique de multiplexage fréquentiel des signaux de lecture. Une seconde teste la fidélité de la porte à deux qubits iSWAP, qui apparait limitée par la décohérence intrinsèque des qubits
This thesis presents our effort to design, fabricate and test a simple 4-Josephson qubit processor with scalability potential. The qubits are frequency tunable and are coupled to a shared coupling bus able to implement iSwap two-qubit gates on any pair of qubits. Each qubit is fitted with its own readout made of a Josephson bifurcation amplifier (JBA). The operation principle of the processor, the choice of parameters, the microwave layout design, as well as the fabrication processes are described. A first experiment demonstrates the simultaneous high-fidelity readout of all the qubits by frequency multiplexing of the JBA signals. A second one tests the two-qubit iSwap gate of the processor, the fidelity of which happens to be limited by the intrinsic qubit decoherence
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Boissonneault, Maxime. "Mesure et rétroaction sur un qubit multi-niveaux en électrodynamique quantique en circuit non linéaire." Thèse, Université de Sherbrooke, 2011. http://savoirs.usherbrooke.ca/handle/11143/5146.

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L'électrodynamique quantique en circuit est une architecture prometteuse pour le calcul quantique ainsi que pour étudier l'optique quantique. Dans cette architecture, on couple un ou plusieurs qubits supraconducteurs jouant le rôle d'atomes à un ou plusieurs résonateurs jouant le rôle de cavités optiques. Dans cette thèse, j'étudie l'interaction entre un seul qubit supraconducteur et un seul résonateur, en permettant cependant au qubit d'avoir plus de deux niveaux et au résonateur d'avoir une non-linéarité Kerr. Je m'intéresse particulièrement à la lecture de l'état du qubit et à son amélioration, à la rétroaction du processus de mesure sur le qubit de même qu'à l'étude des propriétés quantiques du résonateur à l'aide du qubit. J'utilise pour ce faire un modèle analytique réduit que je développe à partir de la description complète du système en utilisant principalement des transformations unitaires et une élimination adiabatique. J'utilise aussi une librairie de calcul numérique maison permettant de simuler efficacement l'évolution du système complet. Je compare les prédictions du modèle analytique réduit et les résultats de simulations numériques à des résultats expérimentaux obtenus par l'équipe de quantronique du CEASaclay. Ces résultats sont ceux d'une spectroscopie d'un qubit supraconducteur couplé à un résonateur non linéaire excité. Dans un régime de faible puissance de spectroscopie le modèle réduit prédit correctement la position et la largeur de la raie. La position de la raie subit les décalages de Lamb et de Stark, et sa largeur est dominée par un déphasage induit par le processus de mesure. Je montre que, pour les paramètres typiques de l'électrodynamique quantique en circuit, un accord quantitatif requiert un modèle en réponse non linéaire du champ intra-résonateur, tel que celui développé. Dans un régime de forte puissance de spectroscopie, des bandes latérales apparaissent et sont causées par les fluctuations quantiques du champ électromagnétique intra-résonateur autour de sa valeur d'équilibre. Ces fluctuations sont causées par la compression du champ électromagnétique due à la non-linéarité du résonateur, et l'observation de leur effet via la spectroscopie d'un qubit constitue une première. Suite aux succès quantitatifs du modèle réduit, je montre que deux régimes de paramètres améliorent marginalement la mesure dispersive d'un qubit avec un résonateur linéaire, et significativement une mesure par bifurcation avec un résonateur non linéaire. J'explique le fonctionnement d'une mesure de qubit dans un résonateur linéaire développée par une équipe expérimentale de l'Université de Yale. Cette mesure, qui utilise les non-linéarités induites par le qubit, a une haute fidélité, mais utilise une très haute puissance et est destructrice. Dans tous ces cas, la structure multi-niveaux du qubit s'avère cruciale pour la mesure. En suggérant des façons d'améliorer la mesure de qubits supraconducteurs, et en décrivant quantitativement la physique d'un système à plusieurs niveaux couplé à un résonateur non linéaire excité, les résultats présentés dans cette thèse sont pertinents autant pour l'utilisation de l'architecture d'électrodynamique quantique en circuit pour l'informatique quantique que pour l'optique quantique.
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Bilmes, Alexander [Verfasser], and Ustinov A. [Akademischer Betreuer] V. "Resolving locations of defects in superconducting transmon qubits / Alexander Bilmes ; Betreuer: A. V. Ustinov." Karlsruhe : KIT Scientific Publishing, 2019. http://d-nb.info/1200547977/34.

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Richer, Susanne [Verfasser], David P. [Akademischer Betreuer] DiVincenzo, and Christoph [Akademischer Betreuer] Stampfer. "Design of an inductively shunted transmon qubit with tunable transverse and longitudinal coupling / Susanne Richer ; David P. DiVincenzo, Christoph Stampfer." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1185442006/34.

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Nguyen, Francois. "Cooper pair box circuits : two‐qubit gate, single‐shot readout, and current to frequency conversion." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2008. http://tel.archives-ouvertes.fr/tel-00390074.

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During this thesis, we have used superconducting circuits with Josephson junctions, derived from the Cooper pair box, in order to implement quantum bits (qubits).
To implement two-qubit gates, we have developed a new circuit, the quantroswap, which consists in two capacitively coupled Cooper pair box, each of them being manipulated and read separately. We have demonstrated coherent exchange of energy between them, but we have also observed a problem of qubit instability.
In order to avoid this spurious effect, we have implemented another circuit based on a charge insensitive split Cooper pair box coupled to a non-linear resonator for readout-out purpose. We have measured large coherence time, and obtained large readout fidelity (90%) using the bifurcation phenomenon.
For metrological purpose, microwave reflectometry measurement on a quantronium also allowed us to relate an applied current I to the frequency f=I/2e of induced Bloch oscillations.
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Peterer, Michael. "Experiments on multi-level superconducting qubits and coaxial circuit QED." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:572f08ef-2d14-4fda-8e18-71f80fc4c47a.

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Superconducting qubits are a promising technology for building a scalable quantum computer. An important architecture employed in the field is called Circuit Quantum Electrodynamics (circuit QED), where such qubits are combined with high quality microwave cavities to study the interaction between artificial atoms and single microwave photons. The ultra-strong coupling achieved in these systems allows for control and readout of the quantum state of qubits to perform quantum information processing. The work on circuit QED performed in this thesis consisted of realizing an experimental setup for qubit experiments in a new laboratory, investigating the coherence and decay of higher energy levels of superconducting transmon qubits and finally demonstrating a novel coaxial form of circuit QED. Designing and building a 3D circuit QED setup involved the following main accomplishments: producing high quality 3D cavities; designing and installing the cryogenic microwave setup as well as the room temperature amplification and data acquisition circuitry; successfully developing a recipe for the fabrication of Josephson junctions; controlling and measuring superconducting 3D transmon qubits at 10mK. Several qubits were fully characterised and have shown coherence times of several microseconds and relaxation times up to 25μs. Superconducting qubits in fact possess higher energy levels that can provide significant computational advantages in quantum information applications. In experiments performed at MIT, preparation and control of the five lowest states of a transmon qubit was demonstrated, followed by an investigation of the phase coherence and decay dynamics of these higher energy levels. The decay was found to proceed mainly sequentially with relaxation times in excess of 20μs for all transitions. A direct measurement of the charge dispersion of these levels was performed to explore their characteristics of dephasing. This experiment was also reproduced on a 3D transmon fabricated and measured in Oxford, where due to a higher effective qubit temperature a multi-level decay model including thermal excitations was developed to explain the observed relaxation dynamics. Finally, a coaxial transmon, which we name the coaxmon, is presented and measured with a coaxial LC readout resonator and input/output coupling ports placed inline along the third dimension. This novel coaxial circuit QED architecture holds great promise for developing a scalable planar grid of qubits to build a quantum computer.
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Book chapters on the topic "Transman qubit"

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Sharma, Ankit, and Manisha J. Nene. "Quantum Information Transmission Using CNOT Gate." In Recent Trends in Intensive Computing. IOS Press, 2021. http://dx.doi.org/10.3233/apc210219.

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We are at the dawn of quantum era; research efforts are been made on quantum information transmission techniques. Properties of quantum mechanics poses unique challenges in terms of wave collapse function, No cloning theorem and reversible operations. Quantum teleportation and quantum entanglement swapping based architecture are utilized to transmit qubit. In this paper we propose an approach to transmit qubits using controlled NOT gate (CNOT) gates and implement it on quantum machine.
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Rau, Jochen. "Communication." In Quantum Theory, 223–60. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780192896308.003.0005.

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This chapter introduces the notions of classical and quantum information and discusses simple protocols for their exchange. It defines the entropy as a quantitative measure of information, and investigates its mathematical properties and operational meaning. It discusses the extent to which classical information can be carried by a quantum system and derives a pertinent upper bound, the Holevo bound. One important application of quantum communication is the secure distribution of cryptographic keys; a pertinent protocol, the BB84 protocol, is discussed in detail. Moreover, the chapter explains two protocols where previously shared entanglement plays a key role, superdense coding and teleportation. These are employed to effectively double the classical information carrying capacity of a qubit, or to transmit a quantum state with classical bits, respectively. It is shown that both protocols are optimal.
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Kenyon, Ian R. "Superconductivity." In Quantum 20/20, 261–84. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198808350.003.0015.

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Superconductivity and the associated Meissner effect are introduced, indicating that superconductors are perfect diamagnetics. Condensation energy is deduced. The London analysis showing how superconductors exclude flux is presented. The BCS microscopic theory is recapitulated: Cooper pairs of electrons are the constituents of the Bose condensate that carries the non-dissipative current. The binding energy of pairs (energy gap below the Fermi sea) is deduced and related to their size and the critical temperature. Dependence of the energy gap on temperature is shown consistent with BCS theory. The Ginzberg–Landau analysis and the spontaneous symmetry breaking in the condensate phase are recounted. Quantization of trapped magnetic flux is shown to be related to superconductor topology. Type-II superconductors are treated. Finally Josephson effects show unambiguously that the condensate is a macroscopic quantum state. Josephson applications are enumerated, including a new voltage standard, SQUIDs and preliminary versions of qubits (transmons) for quantum computing.
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Conference papers on the topic "Transman qubit"

1

Murthy, Akshay. "Systematic Improvements in Transmon Qubit Coherence Enabled by Comprehensive Investigation of Defects and Inhomogeneities." In Systematic Improvements in Transmon Qubit Coherence Enabled by Comprehensive Investigation of Defects and Inhomogeneities. US DOE, 2023. http://dx.doi.org/10.2172/1988485.

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Liu, Chenxu, Edwin Barnes, and Sophia Economou. "Proposal for Generating Complex Microwave Graph States Using Superconducting Circuits." In Quantum 2.0. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/quantum.2022.qtu2a.21.

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We propose to use transmon qubits to construct microwave 2D cluster states and repeater graph states. We design the generation circuits and compare the state fidelities of fixed- versus tunable-frequency transmon devices.
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3

Dasgupta, Samudra, Kathleen E. Hamilton, and Arnab Banerjee. "Characterizing the memory capacity of transmon qubit reservoirs." In 2022 IEEE International Conference on Quantum Computing and Engineering (QCE). IEEE, 2022. http://dx.doi.org/10.1109/qce53715.2022.00035.

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4

Zhou, Yu, Zhihui Peng, Yuta Horiuchi, O. V. Astafiev, and J. S. Tsai. "Efficient Tunable Microwave Single-photon Source Based on Transmon Qubit." In 2019 IEEE International Superconductive Electronics Conference (ISEC). IEEE, 2019. http://dx.doi.org/10.1109/isec46533.2019.8990896.

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Tien, Kevin, Ken Inoue, Scott Lekuch, David J. Frank, Sudipto Chakraborty, Pat Rosno, Thomas Fox, et al. "A Cryo-CMOS Transmon Qubit Controller and Verification with FPGA Emulation." In 2022 Design, Automation & Test in Europe Conference & Exhibition (DATE). IEEE, 2022. http://dx.doi.org/10.23919/date54114.2022.9774702.

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Choi, JeaKyung, Heyok Hwang, and Eunseong Kim. "Power dependent dynamics of the 2nd excited state of a Transmon qubit." In 2022 IEEE International Conference on Quantum Computing and Engineering (QCE). IEEE, 2022. http://dx.doi.org/10.1109/qce53715.2022.00136.

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7

Roth, Thomas E., and Weng C. Chew. "Full-Wave Computation of the Spontaneous Emission Rate of a Transmon Qubit." In 2021 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting (APS/URSI). IEEE, 2021. http://dx.doi.org/10.1109/aps/ursi47566.2021.9704323.

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8

Bardin, J. C. "A Low-Power CMOS Quantum Controller for Transmon Qubits." In 2020 IEEE International Electron Devices Meeting (IEDM). IEEE, 2020. http://dx.doi.org/10.1109/iedm13553.2020.9372108.

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9

Roth, T. E., and W. C. Chew. "Field-based Description of the Coupling between a Transmon Qubit and a Transmission Line Geometry." In 2022 Photonics & Electromagnetics Research Symposium (PIERS). IEEE, 2022. http://dx.doi.org/10.1109/piers55526.2022.9792669.

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Roth, Thomas E. "Finite Element Time Domain Discretization of a Semiclassical Maxwell-Schrödinger Model of a Transmon Qubit." In 2023 IEEE MTT-S International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization (NEMO). IEEE, 2023. http://dx.doi.org/10.1109/nemo56117.2023.10202378.

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