Undoing a weak quantum measurement of a solid-state qubit

Abstract

We propose an experiment which demonstrates the undoing of a weak continuous measurement of a solid-state qubit, so that any unknown initial state is fully restored. The undoing procedure has only a finite probability of success because of the non-unitary nature of quantum measurement, though it is accompanied by a clear experimental indication of whether or not the undoing has been successful. The probability of success decreases with increasing strength of the measurement, reaching zero for a traditional projective measurement. Measurement undoing (``quantum un-demolition'') may be interpreted as a kind of a quantum eraser, in which the information obtained from the first measurement is erased by the second measurement, which is an essential part of the undoing procedure. The experiment can be realized using quantum dot (charge) or superconducting (phase) qubits.

5 pages

References in corpus (2)

• Quantum-Limited Measurement and Information in Mesoscopic Detectors
• Quantum Nondemolition Measurement of a Kicked Qubit

Cited by in corpus (8)

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• Weak measurement of quantum dot spin qubits
• Quantum efficiency of binary-outcome detectors of solid-state qubits
• Measurement Induced Quantum Coherence Recovery
• Measurement-induced entanglement of two superconducting qubits