Fast High-Fidelity Quantum Nondemolition Qubit Readout via a Nonperturbative Cross-Kerr Coupling

Dassonneville, Rémy; Ramos, Tomás; Milchakov, Vladimir; Planat, Luca; Dumur, Étienne; Foroughi, F.; Puertas, Javier; Léger, Sébastien; Bharadwaj, Karthik Srikanth; Delaforce, Jovian; Naud, Cécile; Hasch-Guichard, Wiebke; García-Ripoll, Juan José; Roch, Nicolas; Buisson, Olivier

doi:10.1103/physrevx.10.011045

Cited by 55 publications

(47 citation statements)

References 58 publications

(80 reference statements)

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“…In order to avoid lowering T 1 by the Purcell effect, following the recent nonperturbative design reported in Ref. [53], a cross-Kerr interaction to an ancilla mode could be used for read-out. The limitations on qubit manipulation fidelity can be mitigated with derivative removal via adiabatic gate pulses [54] and by adapting the design to decrease the grAl volume and critical current density, thereby increasing the anharmonicity.…”

Section: Discussionmentioning

confidence: 99%

Implementation of a Transmon Qubit Using Superconducting Granular Aluminum

et al. 2020

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The high kinetic inductance offered by granular aluminum (grAl) has recently been employed for linear inductors in superconducting high-impedance qubits and kinetic inductance detectors. Because of its large critical current density compared to typical Josephson junctions, its resilience to external magnetic fields, and its low dissipation, grAl may also provide a robust source of nonlinearity for strongly driven quantum circuits, topological superconductivity, and hybrid systems. Having said that, can the grAl nonlinearity be sufficient to build a qubit? Here we show that a small grAl volume (10 × 200 × 500 nm 3) shunted by a thin film aluminum capacitor results in a microwave oscillator with anharmonicity α two orders of magnitude larger than its spectral linewidth Γ 01 , effectively forming a transmon qubit. With increasing drive power, we observe several multiphoton transitions starting from the ground state, from which we extract α ¼ 2π × 4.48 MHz. Resonance fluorescence measurements of the j0i → j1i transition yield an intrinsic qubit linewidth γ ¼ 2π × 10 kHz, corresponding to a lifetime of 16 μs, as confirmed by pulsed time-domain measurements. This linewidth remains below 2π × 150 kHz for in-plane magnetic fields up to ∼70 mT.

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Section: Discussionmentioning

confidence: 99%

Implementation of a Transmon Qubit Using Superconducting Granular Aluminum

et al. 2020

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“…Practical implementation of protective quantum measurements is based on the fact that, while we can completely describe a system using the Schrödinger wave, the quantum state in adiabatic measurement does not change throughout the experiment. Adiabatic measurement 5 , 6 , 41 , 42 in addition to other adiabatic processes, such as adiabatic preparation of a state 43 and its transfer 44 , 45 , enables high-fidelity operations in quantum information processing. The adiabatic condition, Eq.…”

Section: Resultsmentioning

confidence: 99%

The Rayleigh–Lorentz invariant for superconducting resonators and optimal adiabatic qubit-information detection

Choi

2021

Sci Rep

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Dynamical properties of a resonator can be analyzed using the Rayleigh–Lorentz invariant which is not an exact constant but varies more or less over time depending on variations of parameters. We investigate the time behavior of this invariant for a superconducting nano-resonator in order for better understanding of qubit-information detection with the resonator. Superconducting resonators which uses parametric resonance in a Josephson junction circuit can be utilized in implementing diverse next generation nano-optic and nano-electronic devices such as quantum computing systems. Through the analyses of the temporal evolution of the invariant, we derive a condition for optimal adiabatic qubit-information detection with the resonator. This condition is helpful for controlling the dynamics of the resonators over long periods of time. It is necessary to consider it when designing a nano-resonator used for quantum nondemolition readouts of qubit states, crucial in quantum computation.

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“…Experimental requirements needed for the successful implementation of this proposal are discussed in the Sec. D of the Appendix, where we argue that both cavity QED [44,87,88] and circuit QED [89][90][91] appear as promising platforms.…”

Section: The Linear Regime Where N Atmentioning

confidence: 88%

“…Second, the fidelity of the generated Fock state is intrinsically limited by measurement error in the atomic readout. High-fidelity atom readout has already been demonstrated for large numbers of atoms in cavity QED [87,88] and for intermediate numbers of qubits in circuit QED [89][90][91].…”

Section: D01 Error Sources In the Cavity Qed And Circuit Qed Implementationmentioning

confidence: 99%

Weakly invasive metrology: quantum advantage and physical implementations

Perarnau-Llobet

Malz

Cirac

2021

Quantum

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We consider the estimation of a Hamiltonian parameter of a set of highly photosensitive samples, which are damaged after a few photons Nabs are absorbed, for a total time T. The samples are modelled as a two mode photonic system, where photons simultaneously acquire information on the unknown parameter and are absorbed at a fixed rate. We show that arbitrarily intense coherent states can obtain information at a rate that scales at most linearly with Nabs and T, whereas quantum states with finite intensity can overcome this bound. We characterise the quantum advantage as a function of Nabs and T, as well as its robustness to imperfections (non-ideal detectors, finite preparation and measurement rates for quantum photonic states). We discuss an implementation in cavity QED, where Fock states are both prepared and measured by coupling atomic ensembles to the cavities. We show that superradiance, arising due to a collective coupling between the cavities and the atoms, can be exploited for improving the speed and efficiency of the measurement.

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Fast High-Fidelity Quantum Nondemolition Qubit Readout via a Nonperturbative Cross-Kerr Coupling

Cited by 55 publications

References 58 publications

Implementation of a Transmon Qubit Using Superconducting Granular Aluminum

Implementation of a Transmon Qubit Using Superconducting Granular Aluminum

The Rayleigh–Lorentz invariant for superconducting resonators and optimal adiabatic qubit-information detection

Weakly invasive metrology: quantum advantage and physical implementations

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