Single microwave-photon detector using an artificial Λ-type three-level system

Inomata, K.; Lin, Zhirong; Koshino, Kazuki; Oliver, William; Tsai, Jaw Shen; Yamamoto, Tsuyoshi; Nakamura, Y.

doi:10.1038/ncomms12303

Cited by 195 publications

(146 citation statements)

References 35 publications

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“…the order of 100 MHz for dispersive couplings of the order of 5 MHz. Finally, we note that although we focused here on a simple microwave photon detector, the CBJJ, the presented parity measurement also works with more sophisticated detectors such as [39,40].…”

Section: Discussionmentioning

confidence: 99%

Towards a heralded eigenstate-preserving measurement of multi-qubit parity in circuit QED

Huembeli

Nigg

2017

Phys. Rev. A

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Eigenstate-preserving multi-qubit parity measurements lie at the heart of stabilizer quantum error correction, which is a promising approach to mitigate the problem of decoherence in quantum computers. In this work we explore a high-fidelity, eigenstate-preserving parity readout for superconducting qubits dispersively coupled to a microwave resonator, where the parity bit is encoded in the amplitude of a coherent state of the resonator. Detecting photons emitted by the resonator via a current biased Josephson junction yields information about the parity bit. We analyse theoretically the measurement back-action in the limit of a strongly coupled fast detector and show that in general such a parity measurement, while approximately Quantum Non-Demolition (QND) is not eigenstate-preserving. To remediate this shortcoming we propose a simple dynamical decoupling technique during photon detection, which greatly reduces decoherence within a given parity subspace. Furthermore, by applying a sequence of fast displacement operations interleaved with the dynamical decoupling pulses, the natural bias of this binary detector can be efficiently suppressed. Finally, we introduce the concept of a heralded parity measurement, where a detector click guarantees successful multi-qubit parity detection even for finite detection efficiency.

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Section: Discussionmentioning

confidence: 99%

Towards a heralded eigenstate-preserving measurement of multi-qubit parity in circuit QED

Huembeli

Nigg

2017

Phys. Rev. A

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“…The current schemes of a single-microwave detector include a few circulators in which microwave photons suffer losses, so our setup might be built in a single superconductor chip without a circulator. The single microwave detectors in [50,51] are equivalent to on-off detectors and only can be used for our scheme with T ≈ 1 due to maintaining a very low average photon number in the detection line. This causes a low success probability to generate the odd SCS.…”

Section: Conclusion and Remarksmentioning

confidence: 99%

“…A single-photon detector is the essence of photonic QI processing and has been very recently demonstrated in experimental circuit-QED [50,51]. Because the energy of microwaves is in general some orders of amplitude weaker than optical photons and their wavelength are about the order of a chip size (milimeters to centimeters), it is very challenging to detect propagating microwave photons, but a technical breakthrough has been developed to build a single microwave detector with a high efficiency and a low dark-count probability.…”

Section: Single-photon Detection With a Bs Tmentioning

confidence: 99%

“…In Ref. [50], four levels of a flux qubit are driven to be in dressed states to absorb a microwave photon in a half-wavelength resonator. Then, the readout of the qubit excited state is performed in a parametric phase-locked oscillator with detection efficiency above 0.6.…”

Section: Single-photon Detection With a Bs Tmentioning

confidence: 99%

“…Using a traveling photon resource from JTWPA/JPA, many interesting experiments have been performed in circuit-QED beyond conventional experiments in quantum optics [46][47][48] and this technical development allows us to investigate traveling microwave qubits through transmission lines corresponding to a photonic QI processing in quantum optics [49]. For example, the most recent experiments have shown the detection schemes of a single microwave photon with excellent detection efficiency [50,51], which will be a key ingredient for traveling-microwave QI processing.…”

Section: Introductionmentioning

confidence: 99%

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Implementation of Traveling Odd Schrödinger Cat States in Circuit-QED

2016

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Abstract:We propose a realistic scheme of generating a traveling odd Schrödinger cat state and a generalized entangled coherent state in circuit quantum electrodynamics (circuit-QED). A squeezed vacuum state is used as the initial resource of nonclassical states, which can be created through a Josephson traveling-wave parametric amplifier, and travels through a transmission line. Because a single-photon subtraction from the squeezed vacuum gives an odd Schrödinger cat state with very high fidelity, we consider a specific circuit-QED setup consisting of the Josephson amplifier creating the traveling resource in a line, a beam-splitter coupling two transmission lines, and a single photon detector located at the end of the other line. When a single microwave photon is detected by measuring the excited state of a superconducting qubit in the detector, a heralded cat state is generated with high fidelity in the opposite line. For example, we show that the high fidelity of the outcome with the ideal cat state can be achieved with appropriate squeezing parameters theoretically. As its extended setup, we suggest that generalized entangled coherent states can be also built probabilistically and that they are useful for microwave quantum information processing for error-correctable qudits in circuit-QED.

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