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Title: Continuous joint measurement and entanglement of qubits in remote cavities

Abstract

We present a first-principles theoretical analysis of the entanglement of two superconducting qubits in spatially separated microwave cavities by a sequential (cascaded) probe of the two cavities with a coherent mode, that provides a full characterization of both the continuous measurement induced dynamics and the entanglement generation. We use the SLH formalism to derive the full quantum master equation for the coupled qubits and cavities system, within the rotating wave and dispersive approximations, and conditioned equations for the cavity fields. We then develop effective stochastic master equations for the dynamics of the qubit system in both a polaronic reference frame and a reduced representation within the laboratory frame. We compare simulations with and analyze tradeoffs between these two representations, including the onset of a non-Markovian regime for simulations in the reduced representation. We provide conditions for ensuring persistence of entanglement and show that using shaped pulses enables these conditions to be met at all times under general experimental conditions. The resulting entanglement is shown to be robust with respect to measurement imperfections and loss channels. Here, we also study the effects of qubit driving and relaxation dynamics during a weak measurement, as a prelude to modeling measurement-based feedback control inmore » this cascaded system.« less

Authors:
 [1];  [1];  [2]
  1. Berkeley Center for Quantum Information and Computation, Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
  2. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1512916
Alternate Identifier(s):
OSTI ID: 1214342
Report Number(s):
SAND-2015-0988J
Journal ID: ISSN 1050-2947; PLRAAN; 665236
Grant/Contract Number:  
AC04-94AL85000
Resource Type:
Accepted Manuscript
Journal Name:
Physical Review. A
Additional Journal Information:
Journal Volume: 92; Journal Issue: 3; Journal ID: ISSN 1050-2947
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English

Citation Formats

Motzoi, Felix, Whaley, K. Birgitta, and Sarovar, Mohan. Continuous joint measurement and entanglement of qubits in remote cavities. United States: N. p., 2015. Web. doi:10.1103/PhysRevA.92.032308.
Motzoi, Felix, Whaley, K. Birgitta, & Sarovar, Mohan. Continuous joint measurement and entanglement of qubits in remote cavities. United States. doi:10.1103/PhysRevA.92.032308.
Motzoi, Felix, Whaley, K. Birgitta, and Sarovar, Mohan. Tue . "Continuous joint measurement and entanglement of qubits in remote cavities". United States. doi:10.1103/PhysRevA.92.032308. https://www.osti.gov/servlets/purl/1512916.
@article{osti_1512916,
title = {Continuous joint measurement and entanglement of qubits in remote cavities},
author = {Motzoi, Felix and Whaley, K. Birgitta and Sarovar, Mohan},
abstractNote = {We present a first-principles theoretical analysis of the entanglement of two superconducting qubits in spatially separated microwave cavities by a sequential (cascaded) probe of the two cavities with a coherent mode, that provides a full characterization of both the continuous measurement induced dynamics and the entanglement generation. We use the SLH formalism to derive the full quantum master equation for the coupled qubits and cavities system, within the rotating wave and dispersive approximations, and conditioned equations for the cavity fields. We then develop effective stochastic master equations for the dynamics of the qubit system in both a polaronic reference frame and a reduced representation within the laboratory frame. We compare simulations with and analyze tradeoffs between these two representations, including the onset of a non-Markovian regime for simulations in the reduced representation. We provide conditions for ensuring persistence of entanglement and show that using shaped pulses enables these conditions to be met at all times under general experimental conditions. The resulting entanglement is shown to be robust with respect to measurement imperfections and loss channels. Here, we also study the effects of qubit driving and relaxation dynamics during a weak measurement, as a prelude to modeling measurement-based feedback control in this cascaded system.},
doi = {10.1103/PhysRevA.92.032308},
journal = {Physical Review. A},
number = 3,
volume = 92,
place = {United States},
year = {2015},
month = {9}
}

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