High-fidelity state transfer between leaky quantum memories

Daniel Soh,Matt Eichenfield,Eric Chatterjee

doi:10.1103/physrevresearch.3.033027

Abstract

Employing the scattering-Lindblad-Hamiltonian formalism description of quantum network theory, we model the general problem of quantum state transfer between two disparate quantum memory blocks in an open quantum system. We derive an analytical expression for the fidelity of quantum state transfer between the memory blocks under the action of a specific phase space trajectory for each of the relevant classical control fields. We find a set of trajectories that maximize the state transfer fidelity between asymmetric systems. We show that, for the example where the mechanical modes of two optomechanical oscillators act as the quantum memory blocks, their optical modes and a waveguide channel connecting them can be used to achieve a quantum state transfer fidelity of 96% with realistic parameters using our optimal control solution. The effects of the intrinsic losses and the asymmetries in the physical memory parameters are discussed quantitatively.

Highlights

Many hybrid quantum systems are being explored to enhance the functionality, scalability, and resource-constrained processing power of near-term quantum information processing systems and networks [1,2,3,4]
An ideal quantum memory is a physical system with a long decoherence time and read and write functions enabled via a controllable coupling to intermediary qubits that can propagate between processing blocks and memory blocks or between memory blocks
If the pulse shapes are solved for by setting the output coupling rate for both blocks to the average value of κex = 2π × 3 GHz, a numerical simulation based on Quantum Toolbox in PYTHON (QUTIP [26]) reveals that the maximum fidelity becomes 73.5%, well below the 89.1% fidelity based on the pulse shapes derived using our method

Summary

Introduction

Many hybrid quantum systems are being explored to enhance the functionality, scalability, and resource-constrained processing power of near-term quantum information processing systems and networks [1,2,3,4]. High-fidelity quantum state transfer will enable key network functions such as entanglement distribution [5] and quantum repeaters [6]. It allows for various distributed quantum information processing architectures [7,8]. An ideal quantum memory is a physical system with a long decoherence time and read and write functions enabled via a controllable coupling to intermediary qubits that can propagate between processing blocks and memory blocks or between memory blocks. Regardless of the physical instantiation of quantum memory architecture, the crucial problem to solve is how to configure the time-varying coupling between the storage and intermediary qubits to accomplish optimal quantum state transfer between memory blocks and other elements

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Methods

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Conclusion