Experimental Demonstration of Instrument-specific Quantum Memory Effects and Non-Markovian Process Recovery for Common-Cause Processes

Abstract

The duration, strength and structure of memory effects are crucial properties of physical evolution. Due to the invasive nature of quantum measurement, such properties must be defined with respect to the probing instruments employed. Here, using a photonic platform, we experimentally demonstrate this necessity via two paradigmatic processes: future-history correlations in the first process can be erased by an intermediate quantum measurement; for the second process, a noisy classical measurement blocks the effect of history. We then apply memory truncation techniques to recover an efficient description that approximates expectation values for multi-time observables. Our proof-of-principle analysis paves the way for experiments concerning more general non-Markovian quantum processes and highlights where standard open systems techniques break down.

4.5+7 pages; 7 figures; 62 references

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• Experimental Aspects of Indefinite Causal Order in Quantum Mechanics
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• Optomechanical second-order sidebands and group delays in a spinning resonator with parametric amplifier and non-Markovian effects
• Noise mitigation in quantum teleportation
• Preserving quantum correlations and coherence with non-Markovianity
• Hidden Quantum Memory: Is Memory There When Somebody Looks?
• Hamiltonian characterisation of multi-time processes with classical memory
• Compression of Entanglement Improves Quantum Communication
• Dressed bound states and non-Markovian dynamics with a whispering-gallery-mode microcavity coupled to a two-level atom and a semi-infinite photonic waveguide
• Purely quantum memory in closed systems observed via imperfect measurements
• Leggett-Garg inequalities for multitime processes
• Robust Error Accumulation Suppression for Quantum Circuits