Mach-Zehnder Interferometry in a Strongly Driven Superconducting Qubit

Oliver, William; Yu, Yang; Boquien, M.; Berggren, Karl K.; Levitov, L. S.; Orlando, Terry P.

doi:10.1126/science.1119678

Cited by 434 publications

(612 citation statements)

References 34 publications

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“…Resolved sidebands appear at o ¼ o 0 ± kO (k ¼ 0,1,2,y), and are amplitude-modulated with Bessel functions J k (d/O), where d and O denote the modulation amplitude and frequency, respectively. The HamiltonianĤ þĤ drive (equations (1) and (4)) can be transformed to a non-uniformly rotating frame 18,19 (see Methods). The theoretical prediction for the steady-state occupation probability on the resolved sidebands ( O4g4G 2 ) is…”

Section: Resultsmentioning

confidence: 99%

“…Even though O ( o 0 , the qubit can be excited with the low-frequency signal in the presence of an additional highfrequency drive o. This can be seen as a multi-photon transition process involving quanta from both fields (in equation (5)), or, as a photon-assisted Landau-ZenerStückelberg (LZS) interference 18,20,21,36 between the dressed states |k, nS and |m, n À 1S. Let us first consider the multi-photon transition processes associated with the sinusoidal-modulated Hamiltonian, defined in equations (1) and (4),…”

Section: Methodsmentioning

confidence: 99%

“…We show below how to eliminate the time-dependence from the longitudinal drive. After moving to a non-uniformly rotating frame with the unitary transformation 18,19 …”

Section: Methodsmentioning

confidence: 99%

“…However, the system can still perform LZS transitions by absorbing a photon from the driving field. This photon-assisted LZS interference can be seen by transforming the HamiltonianĤ þĤ drive from equation (7) into the frame rotating at o around the z axis (unitary transformation U ¼ expð À ioŝ z /2Þ), where it has exactly the same form (in the RWA) as that of LZS interference 18,21,36 , namelŷ…”

Section: Methodsmentioning

confidence: 99%

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Motional averaging in a superconducting qubit

et al. 2013

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Superconducting circuits with Josephson junctions are promising candidates for developing future quantum technologies. Of particular interest is to use these circuits to study effects that typically occur in complex condensed-matter systems. Here we employ a superconducting quantum bit-a transmon-to perform an analogue simulation of motional averaging, a phenomenon initially observed in nuclear magnetic resonance spectroscopy. By modulating the flux bias of a transmon with controllable pseudo-random telegraph noise we create a stochastic jump of its energy level separation between two discrete values. When the jumping is faster than a dynamical threshold set by the frequency displacement of the levels, the initially separate spectral lines merge into a single, narrow, motional-averaged line. With sinusoidal modulation a complex pattern of additional sidebands is observed. We show that the modulated system remains quantum coherent, with modified transition frequencies, Rabi couplings, and dephasing rates. These results represent the first steps towards more advanced quantum simulations using artificial atoms.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…We show below how to eliminate the time-dependence from the longitudinal drive. After moving to a non-uniformly rotating frame with the unitary transformation 18,19 …”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Motional averaging in a superconducting qubit

et al. 2013

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“…In particular, we show that spectroscopic transmission measurements of the junction resonator mode can reveal how the coupling magnitude between the junction and the TLSs varies with an external magnetic field applied in the plane of the tunnel barrier. The proposed experiments offer the possibility of clearly resolving the underlying coupling mechanism for these spurious TLSs, an important decoherence source limiting the quality of superconducting quantum devices.Superconducting quantum circuits have been intensively tested in various regimes in the past few years, from superconducting qubits demonstrating long coherence times, to superconducting transmission line cavities coherently coupled to a Single Cooper Pair box [1,2,3,4,5,6]. Such circuits are extremely sensitive to very small quanta and defect states, and hence have the ability to detect individual microwave photons, charged quasiparticles, as well as spurious TLSs within or near Josephson junction tunnel barriers [7,8,9,10,11].…”

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confidence: 99%

Josephson Junction Microscope for Low-Frequency Fluctuators

Tian

Simmonds

2007

Phys. Rev. Lett.

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The high-Q harmonic oscillator mode of a Josephson junction can be used as a novel probe of spurious two-level systems (TLSs) inside the amorphous oxide tunnel barriers of the junction. In particular, we show that spectroscopic transmission measurements of the junction resonator mode can reveal how the coupling magnitude between the junction and the TLSs varies with an external magnetic field applied in the plane of the tunnel barrier. The proposed experiments offer the possibility of clearly resolving the underlying coupling mechanism for these spurious TLSs, an important decoherence source limiting the quality of superconducting quantum devices.Superconducting quantum circuits have been intensively tested in various regimes in the past few years, from superconducting qubits demonstrating long coherence times, to superconducting transmission line cavities coherently coupled to a Single Cooper Pair box [1,2,3,4,5,6]. Such circuits are extremely sensitive to very small quanta and defect states, and hence have the ability to detect individual microwave photons, charged quasiparticles, as well as spurious TLSs within or near Josephson junction tunnel barriers [7,8,9,10,11]. In recent experiments [10,11], TLSs were identified through spectroscopic measurements of a superconducting phase qubit appearing as 'gaps" or "splittings" in the energy spectrum.The TLS defects can be an unwanted source of decoherence for superconducting quantum bits. The lowfrequency noise, which has been shown to be a serious source of decoherence for superconducting qubits [10,11,12,13,14], is very probably induced by such amorphous fluctuators inside or near Josephson junctions [15,16]. Understanding the origin of these spurious TLSs, their coherent quantum behavior, and their connection to ubiquitous 1/f noise is hence a challenge that will be crucial to the future of superconducting quantum devices. The behavior of a distribution of these TLSs were studied theoretically in [17,18,19]. Recently, it was proposed that TLSs can be viewed as qubits themselves [20], given their relatively long coherence times. However, the microscopic origin and the coupling mechanism between the TLSs and the junction remains unresolved. Generally considered to be connected to the amorphous nature of the tunnel barrier [21], movement of unrestrained atoms or charges may lead to a number of possible coupling mechanisms. As originally proposed in Ref. [11], fluctuations of the TLS could lead to variations of the junction critical current. Another possibility, requires that the TLSs have fluctuating dipole moments which couple to the electric field found within the junction tunnel barrier [10].Here, we present a scheme that can resolve a variety of properties of the TLSs and distinguish between these two suggested coupling mechanisms through the use of an applied magnetic field. Consider a Josephson junction resonator operating as a high-Q, nonlinear cavity mode [22], coupling to a TLS through its canonical phase (or momentum) operator. This forms a cavity QED sys...

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A Deep‐Learning Approach to the Dynamics of Landau–Zenner Transitions

Gao

Sun

Zheng

et al. 2021

Advcd Theory and Sims

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Traditional approaches to the dynamics of the open quantum systems with high precision are often resource intensive. How to improve computation accuracy and efficiency for target systems is an extremely difficult challenge. In this work, combining unsupervised and supervised learning algorithms, a deep-learning approach is introduced to simulate and predict Landau-Zenner dynamics. Data obtained from multiple Davydov D 2 Ansatz with a low multiplicity of four are used for training, while the data from the trial state with a high multiplicity of ten are adopted as target data to assess the accuracy of prediction. After proper training, our method can successfully predict and simulate Landau-Zenner dynamics using only random noise and two adjustable model parameters. Compared to the high-precision dynamics data from multiple Davydov D 2 Ansatz with a multiplicity of ten, the error rate falls below 0.6%.

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Mach-Zehnder Interferometry in a Strongly Driven Superconducting Qubit

Cited by 434 publications

References 34 publications

Motional averaging in a superconducting qubit

Motional averaging in a superconducting qubit

Josephson Junction Microscope for Low-Frequency Fluctuators

A Deep‐Learning Approach to the Dynamics of Landau–Zenner Transitions

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