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Title: Inferring superposition and entanglement in evolving systems from measurements in a single basis

Abstract

We discuss what can be inferred from measurements on evolving one- and two-qubit systems using a single measurement basis at various times. We show that, given reasonable physical assumptions, carrying out such measurements at quarter-period intervals is enough to demonstrate coherent oscillations of one or two qubits between the relevant measurement basis states. One can thus infer from such measurements alone that an approximately equal superposition of two measurement basis states has been created during a coherent oscillation experiment. Similarly, one can infer that a near-maximally entangled state of two qubits has been created part way through an experiment involving a putative SWAP gate. These results apply even if the relevant quantum systems are only approximate qubits. We discuss applications to fundamental quantum physics experiments and quantum-information processing investigations.

Authors:
; ; ;  [1]
  1. Hewlett-Packard Laboratories, Filton Road, Stoke Gifford, Bristol BS34 8QZ (United Kingdom)
Publication Date:
OSTI Identifier:
20636365
Resource Type:
Journal Article
Journal Name:
Physical Review. A
Additional Journal Information:
Journal Volume: 67; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevA.67.052316; (c) 2003 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1050-2947
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; CORRELATIONS; DATA PROCESSING; ENERGY LEVELS; INFORMATION THEORY; OSCILLATIONS; QUANTUM MECHANICS

Citation Formats

Schelpe, Bella, Kent, Adrian, Munro, William, and Spiller, Tim. Inferring superposition and entanglement in evolving systems from measurements in a single basis. United States: N. p., 2003. Web. doi:10.1103/PhysRevA.67.052316.
Schelpe, Bella, Kent, Adrian, Munro, William, & Spiller, Tim. Inferring superposition and entanglement in evolving systems from measurements in a single basis. United States. https://doi.org/10.1103/PhysRevA.67.052316
Schelpe, Bella, Kent, Adrian, Munro, William, and Spiller, Tim. 2003. "Inferring superposition and entanglement in evolving systems from measurements in a single basis". United States. https://doi.org/10.1103/PhysRevA.67.052316.
@article{osti_20636365,
title = {Inferring superposition and entanglement in evolving systems from measurements in a single basis},
author = {Schelpe, Bella and Kent, Adrian and Munro, William and Spiller, Tim},
abstractNote = {We discuss what can be inferred from measurements on evolving one- and two-qubit systems using a single measurement basis at various times. We show that, given reasonable physical assumptions, carrying out such measurements at quarter-period intervals is enough to demonstrate coherent oscillations of one or two qubits between the relevant measurement basis states. One can thus infer from such measurements alone that an approximately equal superposition of two measurement basis states has been created during a coherent oscillation experiment. Similarly, one can infer that a near-maximally entangled state of two qubits has been created part way through an experiment involving a putative SWAP gate. These results apply even if the relevant quantum systems are only approximate qubits. We discuss applications to fundamental quantum physics experiments and quantum-information processing investigations.},
doi = {10.1103/PhysRevA.67.052316},
url = {https://www.osti.gov/biblio/20636365}, journal = {Physical Review. A},
issn = {1050-2947},
number = 5,
volume = 67,
place = {United States},
year = {Thu May 01 00:00:00 EDT 2003},
month = {Thu May 01 00:00:00 EDT 2003}
}