Quantum Thermodynamics Allows Quantum Measurement Without Collapse

Mohit Lal Bera, Manabendra Nath Bera

Published 2019-10-29Version 1

We introduce a reversible quantum measurement process that is capable of characterizing an unknown state of a system without inducing a collapse or disturbance into it. The underlying idea is to extract information of a system from the thermodynamic quantities like work(s) and heat in a measurement process, thereby uncovering a fundamental correspondence between information and thermodynamics. We establish an improved notion of information isolation and show that a process is isolated if it respects the first law of quantum thermodynamics. The measurement involves a unitary evolution of the system and the apparatus, implemented by a thermodynamically reversible process. The full information about the system is accessed by counting the charge-wise work costs to implement the process. After the measurement, the process is undone and the initial state of the system is retrieved deterministically. The protocol is also capable of characterizing an unknown quantum operation without disturbance or collapse. Fundamentally, our findings make an important step towards resolving the paradoxes arising from the quantum measurement problem, such as the Wigner's friend paradox. The apparent measurement induced collapse can now be understood as the consequence of the ignorance committed by disregarding the quantum thermodynamical aspects of the measurement process and the quantum correlation between system and apparatus. The findings also conclude that quantum mechanics is not inherently indeterministic and it respects realism -- the objective reality of quantum states. On the applied level, the results demand re-investigation of the quantum information and technological protocols that rely on the assumptions of unavoidable measurement induced disturbance and impossibility of copying arbitrary quantum states and operations, such as the quantum key distribution and quantum error correction.