Uncollapsing the wavefunction by undoing quantum measurements

Abstract

We review and expand on recent advances in theory and experiments concerning the problem of wavefunction uncollapse: Given an unknown state that has been disturbed by a generalized measurement, restore the state to its initial configuration. We describe how this is probabilistically possible with a subsequent measurement that involves erasing the information extracted about the state in the first measurement. The general theory of abstract measurements is discussed, focusing on quantum information aspects of the problem, in addition to investigating a variety of specific physical situations and explicit measurement strategies. Several systems are considered in detail: the quantum double dot charge qubit measured by a quantum point contact (with and without Hamiltonian dynamics), the superconducting phase qubit monitored by a SQUID detector, and an arbitrary number of entangled charge qubits. Furthermore, uncollapse strategies for the quantum dot electron spin qubit, and the optical polarization qubit are also reviewed. For each of these systems the physics of the continuous measurement process, the strategy required to ideally uncollapse the wavefunction, as well as the statistical features associated with the measurement is discussed. We also summarize the recent experimental realization of two of these systems, the phase qubit and the polarization qubit.

19 pages, 4 figures

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Cited by in corpus (26)

• Decoherence suppression by uncollapsing
• Balance between information gain and reversibility in weak measurement
• Recent progress in quantum simulation using superconducting circuits
• Arrow of Time for Continuous Quantum Measurement
• Rapid estimation of drifting parameters in continuously measured quantum systems
• Fluctuation Theorems for Continuous Quantum Measurement and Absolute Irreversibility
• Measuring Fluorescence to Track a Quantum Emitter's State: A Theory Review
• Generalized partial measurements
• A quantum no-reflection theorem and the speeding up of Grover's search algorithm
• Global triplewise information trade-off in quantum measurement
• Extraction of information from a single quantum
• Partial measurements and the realization of quantum-mechanical counterfactuals
• Linear feedback stabilization of a dispersively monitored qubit
• Complete Information Balance in Quantum Measurement
• Thermodynamics of Quantum Measurement and the Demon's Arrow of Time
• Implementing generalized measurements with superconducting qubits
• Markovian and non-Markovian quantum measurements
• Entanglement-Preserving Limit Cycles from Sequential Quantum Measurements and Feedback
• Bounding the Minimum Time of a Quantum Measurement
• Time reversal symmetry of generalized quantum measurements with past and future boundary conditions
• Reading a Single Qubit System Using Weak Measurement with Variable Strength
• Enhancing quantum state transfer efficiency in binary-tree spin networks by partially collapsing measurements
• Unlearning Quantum Information
• Logically reversible measurements: Construction and application
• Time Derivatives of Weak Values
• Quantum Measurement Induced Radiative Processes in Continuously Monitored Optical Environments