Energy Relaxation Time between Macroscopic Quantum Levels in a Superconducting Persistent-Current Qubit

Yu, Yang; Nakada, D.; Boquien, M.; Singh, Bhagwan; Crankshaw, D.S.; Orlando, Terry P.; Berggren, Karl K.; Oliver, William

doi:10.1103/physrevlett.92.117904

Cited by 38 publications

(25 citation statements)

References 23 publications

(61 reference statements)

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“…Under similar bias conditions the rate Γ 3→1 + Γ 3→2 ≈ (25 µs) −1 (experimentally measured in [40]) is much slower than Γ…”

Section: A the Pc-qubit Modelmentioning

confidence: 63%

“…The relative depth of the two wells can be adjusted by detuning the flux bias to either side of the symmetric point f = 1/2. The potential wells exhibit quantized energy levels corresponding to the quantum states of the macroscopic circulating current [38,39,40,41], with the number of levels on each side determined by the depth and frequencies of the wells. In this basis the Hamiltonian can be written…”

Section: A the Pc-qubit Modelmentioning

confidence: 99%

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Electromagnetically induced transparency in superconducting quantum circuits: Effects of decoherence, tunneling, and multilevel crosstalk

et al. 2006

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We explore theoretically electromagnetically-induced transparency (EIT) in a superconducting quantum circuit (SQC). The system is a persistent-current flux qubit biased in a Λ configuration. Previously [Phys.Rev. Lett. 93, 087003 (2004)], we showed that an ideally-prepared EIT system provides a sensitive means to probe decoherence. Here, we extend this work by exploring the effects of imperfect dark-state preparation and specific decoherence mechanisms (population loss via tunneling, pure dephasing, and incoherent population exchange). We find an initial, rapid population loss from the Λ system for an imperfectly prepared dark state. This is followed by a slower population loss due to both the detuning of the microwave fields from the EIT resonance and the existing decoherence mechanisms. We find analytic expressions for the slow loss rate, with coefficients that depend on the particular decoherence mechanisms, thereby providing a means to probe, identify, and quantify various sources of decoherence with EIT. We go beyond the rotating wave approximation to consider how strong microwave fields can induce additional off-resonant transitions in the SQC, and we show how these effects can be mitigated by compensation of the resulting AC Stark shifts.

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“…Under similar bias conditions the rate Γ 3→1 + Γ 3→2 ≈ (25 µs) −1 (experimentally measured in [40]) is much slower than Γ…”

Section: A the Pc-qubit Modelmentioning

confidence: 63%

Section: A the Pc-qubit Modelmentioning

confidence: 99%

Electromagnetically induced transparency in superconducting quantum circuits: Effects of decoherence, tunneling, and multilevel crosstalk

et al. 2006

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“…Note that SQUIDs with these parameters are readily available at the present time [22,23,52]. With the choice of these parameters, the SQUIDs have the desired three-level structure as depicted in Fig.…”

Section: Discussionmentioning

confidence: 99%

n-qubit-controlled phase gate with superconducting quantum-interference devices coupled to a resonator

Yang

Han

2005

Phys. Rev. A

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We present a way to realize a n-qubit controlled phase gate with superconducting quantum interference devices (SQUIDs) by coupling them to a superconducting resonator. In this proposal, the two logical states of a qubit are represented by the two lowest levels of a SQUID. An intermediate level of each SQUID is utilized to facilitate coherent control and manipulation of quantum states of the qubits. It is interesting to note that a n-qubit controlled phase gate can be achieved with n SQUIDs by successively applying a π/2 Jaynes-Cummings pulse to each of the n − 1 control SQUIDs before and after a π Jaynes-Cummings pulse on the target SQUID.

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“…For the sake of definitiveness, let us estimate the experimental feasibility of realizing the logic gates using SQUIDs with the parameters already available in present experiment [31,32,33]. Suppose the quality factor of the superconducting cavity is Q = 1 × 10 6 and the cavity mode frequency is ω c = 50GHz, the cavity decay time is k −1 = Q/ω c = 20µs.…”

Section: Discussionmentioning

confidence: 99%

Quantum controlled phase gate and cluster states generation via two superconducting quantum interference devices in a cavity

et al. 2006

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A scheme for implementing 2-qubit quantum controlled phase gate (QCPG) is proposed with two superconducting quantum interference devices (SQUIDs) in a cavity. The gate operations are realized within the two lower flux states of the SQUIDs by using a quantized cavity field and classical microwave pulses. Our scheme is achieved without any type of measurement, does not use the cavity mode as the data bus and only requires a very short resonant interaction of the SQUID-cavity system. As an application of the QCPG operation, we also propose a scheme for generating the cluster states of many SQUIDs.

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Energy Relaxation Time between Macroscopic Quantum Levels in a Superconducting Persistent-Current Qubit

Cited by 38 publications

References 23 publications

Electromagnetically induced transparency in superconducting quantum circuits: Effects of decoherence, tunneling, and multilevel crosstalk

Electromagnetically induced transparency in superconducting quantum circuits: Effects of decoherence, tunneling, and multilevel crosstalk

n-qubit-controlled phase gate with superconducting quantum-interference devices coupled to a resonator

Quantum controlled phase gate and cluster states generation via two superconducting quantum interference devices in a cavity

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