Erratum: Observation of Measurement-Induced Entanglement and Quantum Trajectories of Remote Superconducting Qubits [Phys. Rev. Lett.<b>112</b>, 170501 (2014)]

Roch, N.; Schwartz, Maurice L.; Motzoi, Felix; Macklin, Chris; Vijay, R.; Eddins, Andrew; Korotkov, Alexander N.; Whaley, K. Birgitta; Sarovar, Mohan; Siddiqi, Irfan

doi:10.1103/physrevlett.114.259901

Cited by 54 publications

(107 citation statements)

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“…As analyzed in [34], it is possible using a dispersive homodyne readout to implement a half-parity measurement in the superconducting circuit architecture. In reference [4], authors succeeded in applying this measurement to two superconducting transmon qubits separated by over a meter. This measurement is characterized by the operatorX…”

Section: Entanglement Via Measurementmentioning

confidence: 99%

“…During this time interval one can then perform feedback on the system based on information already gained. The measured value of the observableX is obtained from a homodyne measurement of the voltage, V [4]. During the measurement, the time-dependent homodyne voltage that constitutes the measurement signal is specified by [35] …”

Section: Entanglement Via Measurementmentioning

confidence: 99%

“…In this work, we build upon this literature in our goal to achieve optimal protocols for remote entanglement, focusing in particular on joint measurements that have been implemented in superconducting qubits [4]. We motivate our approach by an examination of optimality for the state update in a single, discrete time step and define an average sense locally optimal (ASLO) strategy that makes the state update over this discrete time step using the most recent measurement outcome and knowledge of the average state.…”

Section: Introductionmentioning

confidence: 99%

“…Instead, measurement occurs over a finite, resolvable time scale in such systems. Recent research has taken advantage of this by utilizing the fact that continuous weak measurement enables direct observation of the continuous time evolution of a quantum system (quantum trajectories) [1][2][3][4], and also permits operations on the system during the measurement process, including feedback and feed-forward control [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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Deterministic generation of remote entanglement with active quantum feedback

Martin¹,

Motzoi²,

Li³

et al. 2015

Phys. Rev. A

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We consider the task of deterministically entangling two remote qubits using joint measurement and feedback, but no directly entangling Hamiltonian. In order to formulate the most effective experimentally feasible protocol, we introduce the notion of average sense locally optimal (ASLO) feedback protocols, which do not require real-time quantum state estimation, a difficult component of real-time quantum feedback control. We use this notion of optimality to construct two protocols which can deterministically create maximal entanglement: a semiclassical feedback protocol for low efficiency measurements and a quantum feedback protocol for high efficiency measurements. The latter reduces to direct feedback in the continuous-time limit, whose dynamics can be modeled by a Wiseman-Milburn feedback master equation which yields an analytic solution in the limit of unit measurement efficiency. Our formalism can smoothly interpolate between continuous-time and discrete-time descriptions of feedback dynamics, and we exploit this feature to then derive a superior hybrid protocol for arbitrary non-unit measurement efficiency that switches between quantum and semiclassical protocols. Finally, we show using simulations incorporating experimental imperfections that deterministic entanglement of remote superconducting qubits may be achieved with current technology using the continuous-time feedback protocol alone.

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Section: Entanglement Via Measurementmentioning

confidence: 99%

Section: Entanglement Via Measurementmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Deterministic generation of remote entanglement with active quantum feedback

Martin¹,

Motzoi²,

Li³

et al. 2015

Phys. Rev. A

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“…In our 3D-Transmon circuit, the qubit energy, i.e. the level splitting of its two lowest levels, is fixed at ω q /2π = 3.58 GHz and not tuneable as in other designs [31][32][33][34][35] . Each datapoint results from a series of individual measurements, each time resonantly exciting the qubit and detecting the qubit population after waiting for some time t. The resulting traces where fitted to an exponential decay curve ∝ e −Γ1t .…”

Section: Experimental Evidencementioning

confidence: 99%

Interacting two-level defects as sources of fluctuating high-frequency noise in superconducting circuits

et al. 2015

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Since the very first experiments, superconducting circuits have suffered from strong coupling to environmental noise, destroying quantum coherence and degrading performance. In state-of-the-art experiments, it is found that the relaxation time of superconducting qubits fluctuates as a function of time. We present measurements of such fluctuations in a 3D-Transmon circuit and develop a qualitative model based on interactions within a bath of background two-level systems (TLS) which emerge from defects in the device material. In our model, the time-dependent noise density acting on the qubit emerges from its near-resonant coupling to high-frequency TLS which experience energy fluctuations due to their interaction with thermally fluctuating TLS at low frequencies. We support the model by providing experimental evidence of such energy fluctuations observed in a single TLS in a phase qubit circuit.

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Universal Distributed Quantum Computing on Superconducting Qutrits with Dark Photons

et al. 2018

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We present a one-step scheme to construct the controlled-phase gate deterministically on remote transmon qutrits coupled to different resonators connected by a superconducting transmission line for an universal distributed quantum computing. Different from previous works on remote superconducting qubits, the present gate is implemented with coherent evolutions of the entire system in the all-resonance regime assisted by the dark photons to robust against the transmission line loss, which allows the possibility of the complex designation of a long-length transmission line to link lots of circuit QEDs. The length of the transmission line can reach the scale of several meters, which makes our scheme is suitable for the large-scale distributed quantum computing. This gate is a fast quantum entangling operation with a high fidelity of about 99%. Compare with previous works in other quantum systems for a distributed quantum computing, under the all-resonance regime, the present proposal does not require classical pulses and ancillary qubits, which relaxes the difficulty of its implementation largely.

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Erratum: Observation of Measurement-Induced Entanglement and Quantum Trajectories of Remote Superconducting Qubits [Phys. Rev. Lett.112, 170501 (2014)]

Cited by 54 publications

References 0 publications

Deterministic generation of remote entanglement with active quantum feedback

Deterministic generation of remote entanglement with active quantum feedback

Interacting two-level defects as sources of fluctuating high-frequency noise in superconducting circuits

Universal Distributed Quantum Computing on Superconducting Qutrits with Dark Photons

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