Rapid characterization of microscopic two-level systems using Landau-Zener transitions in a superconducting qubit

Tan, Xinsheng; Yu, Haifeng; Yu, Yang; Han, Siyuan

doi:10.1063/1.4930201

Cited by 5 publications

(4 citation statements)

References 28 publications

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“…* Micrometer-size superconducting qubits allow the realization of macroscopically distinct quantum states. The nonadiabatic transitions between them were demonstrated for a variety of JJ-based qubits, namely flux (Izmalkov et al, 2004), quantronium (Ithier et al, 2005), charge (Cooper pair sluice) (Gasparinetti et al, 2012), and phase (Tan et al, 2015) qubits. In these works, it was demonstrated that such measurements are useful for probing and controlling both the qubits themselves and the coupled microscopic systems, hence providing a fast and sensitive tool.…”

Section: Some Experimental Observationsmentioning

confidence: 99%

Quantum Control via Landau-Zener-Stückelberg-Majorana Transitions

Ivakhnenko¹,

Shevchenko²,

Nori³

2022

Preprint

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H. Comparison of different methods IV. Interferometry A. Superconducting circuits B. Semiconductor quantum dots C. Donors and impurities (atomic qubits) D. Graphene E. Microscopic systems F. Other systems G. Multilevel systems V. Quantum control A. Coherent control of microscopic and mesoscopic structures B. Universal single-and two-qubit control C. Shortcuts to adiabaticity D. Adiabatic quantum computation VI. Related classical coherent phenomena VII. Conclusion 1. With near-adiabatic limit (Landau) 2. With parabolic cylinder functions (Zener) 3. With contour integrals (Majorana) 4. With WKB approximation and phase integral method (Stückelberg) 5. Duration of the LZSM transition B. Description of a periodically driven two-level system 1. Adiabatic-impulse model a. Adiabatic evolution b. Multiple-passage evolution 2. Rotating-wave approximation (RWA) 3. Floquet theory 4. Rate equation and white noise approach a. Transition rate b. Rate equation c. From Bessel to Airy d. Double-passage regime ReferencesAbbreviations and most-often-used symbols Because this review article is quite long, for the readers' convenience, we present the main abbreviations used. This list also includes some of the topics covered.

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Section: Some Experimental Observationsmentioning

confidence: 99%

Quantum Control via Landau-Zener-Stückelberg-Majorana Transitions

Ivakhnenko¹,

Shevchenko²,

Nori³

2022

Preprint

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“…where ω max /2π = 5423.5 MHz, ω c /2π = 23.7 MHz, d = −0.2447, M = 2.062, and V 0 = −0.0043 V, respectively. Due to the large junction area (≈1 µm 2 ), previous experiments have revealed characteristic level avoidance or anti-crossing on superconducting phase qubits [18][19][20][21][22], flux qubits [23,24], and Quantronium [25]. However, the junction area of the Xmon qubit used in this experiment is ≈200 nm 2 , and the spectroscopy in Figure 1b shows no obvious anti-crossing.…”

Section: Device and Methodsmentioning

confidence: 59%

“…TLS defects have been investigated using different methods based on superconducting qubits, such as direct microwave spectroscopy [18][19][20][21][22][23][24][25], strain spectroscopy [26][27][28], longterm time-domain measurement [29][30][31][32][33][34], dielectric loss and participation ratio [35][36][37]. These works partially analyze spectral or temporal data, or demonstrate with fixed-frequency qubits.…”

Section: Introductionmentioning

confidence: 99%

Locating Two-Level Systems in a Superconducting Xmon Qubit

Yang

Guo

et al. 2023

Applied Sciences

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One significant source of decoherence in superconducting circuits is known as two-level systems (TLSs), found in amorphous oxide layers. These circuits can, however, also be utilized as spectral and temporal TLS probes. Comprehensive investigations on the physics of TLSs are now possible thanks to recent advancements in superconducting qubits. Here, we simultaneously measure the tunable Xmon qubit decoherence time as well as the resonance frequency for more than 3 days to investigate stochastic fluctuations. Time-domain Allan deviation and frequency-domain power spectral density analysis indicate that two TLSs in near resonance with the qubit are responsible for the fluctuations. From the extracted oscillation in T1 decay, we locate the two TLSs near the junctions.

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“…Superconducting quantum bits (qubits) [1] play a central role in superconducting quantum circuits, which are a promising candidate for solid-state quantum computing [2] and can serve as an excellent platform for the studies of quantum optics [3] and quantum simulation. [4] In addition to the various types of qubits such as charge, flux, and transmon (or Xmon), [1] the superconducting phase qubits [5][6][7][8][9][10][11][12][13][14][15][16][17] have been received much attention in the past years due to their unique properties and advantages. It is known that the phase qubit has a widely tunable anharmonicity α ranging from 0.1% to 10%, and it is convenient to couple the qubits capacitively or inductively, leading to the rich Hamiltonians that are desirable for developing circuit architectures for quantum simulators.…”

Section: Introductionmentioning

confidence: 99%

Superconducting phase qubits with shadow-evaporated Josephson junctions

Su¹,

Liu²,

Xu³

et al. 2017

Chinese Phys. B

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We develop a fabrication process for the superconducting phase qubits in which Josephson junctions for both the qubit and superconducting quantum interference device (SQUID) detector are prepared by shadow evaporation with a suspended bridge. Al junctions with areas as small as 0.05 µm 2 are fabricated for the qubit, in which the number of the decoherencecausing two-level systems (TLS) residing in the tunnel barrier and proportional to the junction area are greatly reduced. The measured energy spectrum shows no avoided crossing arising from coherent TLS in the experimentally reachable flux bias range of the phase qubit, which demonstrates the energy relaxation time T 1 and dephasing time T ϕ on the order of 100 ns and 50 ns, respectively. We discuss several possible origins of decoherence from incoherent or weakly-coupled coherent TLS and further improvements of the qubit performance.

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Rapid characterization of microscopic two-level systems using Landau-Zener transitions in a superconducting qubit

Cited by 5 publications

References 28 publications

Quantum Control via Landau-Zener-Stückelberg-Majorana Transitions

Quantum Control via Landau-Zener-Stückelberg-Majorana Transitions

Locating Two-Level Systems in a Superconducting Xmon Qubit

Superconducting phase qubits with shadow-evaporated Josephson junctions

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