Measuring a Topological Transition in an Artificial Spin-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:math>System

Schroer, M. D.; Kolodrubetz, Michael; Kindel, William; Sandberg, Martin; Gao, Jin-Hua; Vissers, Michael; Pappas, David P.; Polkovnikov, Anatoli; Lehnert, K. W.

doi:10.1103/physrevlett.113.050402

Cited by 160 publications

(159 citation statements)

References 41 publications

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“…This has been demonstrated in two experiments with superconducting qubits [267,268]. Differently from the work on geometric phases, as we show below, the measurement technique in these works is not an interferometric scheme.…”

Section: Topological Transitionsmentioning

confidence: 94%

“…In a) the vector wraps the sphere, and this phase is topologically nontrivial with the first Chern number Ch 1 = 1. In b) the phase is topologically trivial, Ch 1 = 0. c) Phase diagram showing the expected transition between the two phases at δ 0 = δ r , obtained experimentally in references [267,268] by measuring the Berry curvature and using equation (168). Now, the possibility of controlling the detuning δ d in these systems enables the adiabatic exploration of this ellipsoidal manifold, see figure 13.…”

Section: Topological Transitionsmentioning

confidence: 99%

“…In the diagrams below, the Bloch vector is represented as an arrow for each point on the surface of the ellipsoid in the coordinates ξ x , ξ y , and ξ z . For a perfect adiabatic transport, the angle ϕ from the σ x axis on the Bloch sphere should equal φ (both are zero in the experiments in references [267,268]). Nonadiabaticity produces shifts in the Bloch vectors away from the plane ϕ = 0, and this leads to a measurable response function which, in the first order in the speed v χ = dχ/dt, is precisely the Berry curvature.…”

Section: Topological Transitionsmentioning

confidence: 99%

“…The quantity σ y is obtained by performing quantum tomography at each time, that is, at each point in the parameter space [268]. From the values of the Berry curvature, the Chern number can be calculated by integration, using the symmetry with respect to φ,…”

Section: Topological Transitionsmentioning

confidence: 99%

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Quantum systems under frequency modulation

et al. 2017

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Abstract. We review the physical phenomena that arise when quantum mechanical energy levels are modulated in time. The dynamics resulting from changes in the transition frequency is a problem studied since the early days of quantum mechanics. It has been of constant interest both experimentally and theoretically since, with the simple two-state model providing an inexhaustible source of novel concepts. When the transition frequency of a quantum system is modulated, several phenomena can be observed, such as Landau-Zener-Stückelberg-Majorana interference, motional averaging and narrowing, and the formation of dressed states with the presence of sidebands in the spectrum. Adiabatic changes result in the accumulation of geometric phases, which can be used to create topological states. In recent years, an exquisite experimental control in the time domain was gained through the parameters entering the Hamiltonian, and high-fidelity readout schemes allowed the state of the system to be monitored non-destructively. These developments were made in the field of quantum devices, especially in superconducting qubits, as a well as in atomic physics, in particular in ultracold gases. As a result of these advances, it became possible to demonstrate many of the fundamental effects that arise in a quantum system when its transition frequencies are modulated. The purpose of this review is to present some of these developments, from two-state atoms and harmonic oscillators to multilevel and many-particle systems.

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Section: Topological Transitionsmentioning

confidence: 94%

Section: Topological Transitionsmentioning

confidence: 99%

Section: Topological Transitionsmentioning

confidence: 99%

Section: Topological Transitionsmentioning

confidence: 99%

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Quantum systems under frequency modulation

et al. 2017

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“…These circuit elements can be used to emulate fermionic and bosonic degrees of freedom in a broad range of many-body problems, including quantum spin systems [7][8][9][10][11][12][13][14][15][16], coupled cavity array models [17][18][19], topological phases [20,21], and electron-phonon physics [22,23]. Recent experiments have demonstrated arrays of quantum spins coupled simultaneously to one resonator [24], switching of the Chern number on one or two qubits [25,26] and weak localization of superconducting qubits [27].…”

Section: Introductionmentioning

confidence: 99%

Superconducting circuit probe for analog quantum simulators

You

Tian

2015

Phys. Rev. A

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Analog quantum simulators can be used to study quantum correlation in novel many-body systems by emulating the Hamiltonian of these systems. One essential question in quantum simulation is to probe the properties of an emulated many-body system. Here we present a circuit QED scheme for probing such properties by measuring the spectrum of a superconducting resonator coupled to a quantum simulator. We first study a general framework of this approach, and show that the spectrum of the resonator is directly related to the correlation function of the coupling operator between the resonator and the simulator. We then apply this scheme to a simulator of the transverse field Ising model implemented with superconducting qubits, where the resonance peaks in the resonator spectrum correspond to the frequencies of the elementary excitations. The effects of resonator damping, qubit decoherence, and resonator backaction are also discussed. This setup can be used to probe a broad range of many-body models.

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Broadband and Fabrication Tolerant Power Coupling and Mode‐Order Conversion Using Thouless Pumping Mechanism

Sun

Wang

et al. 2022

Laser & Photonics Reviews

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Coupled‐waveguide devices are of central importance in on‐chip photonic circuits. However, their performance usually suffers from high wavelength and structure sensitivity, which makes it challenging to achieve broadband and fabrication tolerant optical functions. Topological pumping of edge states has emerged as a promising route for robust light transport in coupled waveguides. Here, the Thouless pumping process is explored in finite Rice‐Mele modeled silicon waveguide arrays and the robust power coupling and mode‐order conversion are experimentally demonstrated in this system. Thanks to the topological protection of light transport, the directional coupler and mode‐order converter based on the waveguide arrays show an ultrabroad bandwidth of 120 nm and are quite tolerant to significant structural deviations (−50–150 nm). As compared to the robust optical coupling in other topological waveguide arrays reported in recent works, the approach is more advantageous in terms of robustness against the variations in both waveguide width and gap distance, which is greatly favored in large‐scale photonic integration. This work could serve as a design principle for a new class of broadband and fabrication tolerant coupled‐waveguide devices, which can find applications in many fields including optical simulations of condensed matter physics, on‐chip optical communications, and quantum information processing.

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Measuring a Topological Transition in an Artificial Spin-1/2System

Cited by 160 publications

References 41 publications

Quantum systems under frequency modulation

Quantum systems under frequency modulation

Superconducting circuit probe for analog quantum simulators

Broadband and Fabrication Tolerant Power Coupling and Mode‐Order Conversion Using Thouless Pumping Mechanism

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