High-efficiency tomographic reconstruction of quantum states by quantum nondemolition measurements

Journal Article · Tue Mar 15 00:00:00 EDT 2011 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.83.032110· OSTI ID:21537382

Huang, J S ^[1]; Wei, L F ^[1]; Oh, C H ^[2]

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1. Quantum Optoelectronics Laboratory, School of Physics and Technology, Southwest Jiaotong University, Chengdu 610031 (China)
2. Centre for Quantum Technologies and Department of Physics, National University of Singapore, 3 Science Drive 2, Singapore 117542 (Singapore)

We propose a high-efficiency scheme to tomographically reconstruct an unknown quantum state by using a series of quantum nondemolition (QND) measurements. The proposed QND measurements of the qubits are implemented by probing the stationary transmissions through a driven dispersively coupled resonator. It is shown that only one kind of QND measurement is sufficient to determine all the diagonal elements of the density matrix of the detected quantum state. The remaining nondiagonal elements can be similarly determined by transferring them to the diagonal locations after a series of unitary operations. Compared with the tomographic reconstructions based on the usual destructive projective measurements (wherein one such measurement can determine only one diagonal element of the density matrix), the present reconstructive approach exhibits significantly high efficiency. Specifically, our generic proposal is demonstrated by the experimental circuit quantum electrodynamics systems with a few Josephson charge qubits.

• OSTI ID: 21537382
• Journal Information: Physical Review. A, Vol. 83, Issue 3; Other Information: DOI: 10.1103/PhysRevA.83.032110; (c) 2011 American Institute of Physics; ISSN 1050-2947
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
DENSITY MATRIX
EFFICIENCY
QUANTUM ELECTRODYNAMICS
QUANTUM STATES
QUBITS
RESONATORS
TRANSMISSION
ELECTRODYNAMICS
ELECTRONIC EQUIPMENT
EQUIPMENT
FIELD THEORIES
INFORMATION
MATRICES
QUANTUM FIELD THEORY
QUANTUM INFORMATION