The paper discusses the optimization of open quantum harmonic oscillator (OQHO) systems as quantum memories. OQHOs are modeled using linear quantum stochastic differential equations, where the system variables (positions and momenta) interact with external quantum fields.
The key insights are:
A partially isolated subsystem of the OQHO can be identified, where the subsystem variables are affected by the external fields only indirectly through another subsystem. This partial isolation leads to a qualitatively different short-horizon asymptotic behavior of the mean-square deviation of the subsystem variables from their initial values, yielding a longer decoherence time in the high-fidelity limit.
The memory decoherence time, defined as the time horizon at which the weighted mean-square deviation of the system variables from their initial values reaches a given fidelity threshold, can be maximized over the energy parameters of the OQHO to improve its performance as a quantum memory.
For a coherent feedback interconnection of two OQHOs with direct energy coupling and indirect field-mediated coupling, the optimal direct energy coupling matrix is characterized as the solution to a linear matrix equation.
The analysis provides a systematic approach to optimizing the performance of partially isolated OQHO subsystems as quantum memories by exploiting their unique asymptotic properties.
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arxiv.org
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by Igor G. Vlad... : arxiv.org 09-25-2024
https://arxiv.org/pdf/2409.15720.pdfDaha Derin Sorular