Parallel Quantum Computation of Vibrational Dynamics

Ksenia Komarova,R D Levine,F Remacle,Hugo Gattuso

doi:10.3389/fphy.2020.590699

Abstract

The vibrational dynamics in a linear triatomic molecule is emulated by a quantum information processing device operating in parallel. The quantum device is an ensemble of semiconducting quantum dot dimers addressed and probed by ultrafast laser pulses in the visible frequency range at room temperature. A realistic assessment of the inherent noise due to the inevitable size dispersion of colloidal quantum dots is taken into account and limits the time available for computation. At the short times considered only the electronic states of the quantum dots respond to the excitation. We show how up to 82 = 64 quantum logic variables can be realistically measured and used to process information. This is achieved by addressing the lowest and second excited electronic states of the quantum dots. With a narrower laser bandwidth (= longer pulse) only the lower band of excited states can be coherently addressed enabling 42 = 16 logic variables. Already this is sufficient to emulate both energy transfer between the two oscillators and coherent motions in the vibrating molecule.

Highlights

We describe the theoretical background for an experimental setup, an ensemble of quantum dot dimers that can and has been realized in the laboratory
On the right side of the figure we show relevant segments of 2D frequency maps computed at different values of the time interval T that enable the device to simulate the two functions of time 〈R〉(t) and σ2R(t)
A versatile quantum mechanical computing device that operates on a laser addressed solid array of quantum dots dimers has been discussed

Summary

Introduction

We describe the theoretical background for an experimental setup, an ensemble of quantum dot dimers that can and has been realized in the laboratory. We show explicitly how this device is used to emulate the quantum vibrational dynamics of a linear triatomic molecule and discuss possible extensions. In 1985 Deutsch defined a quantum computer as a device that could simulate effectively an arbitrary physical system [1]. We seek to describe a device that can be realized with currently available laboratory techniques. The device needs to provide computational answers only for a limited set of variables of the physical system. The computation is realized by mapping of the dynamics of the physical variables of this limited set using a set of observations of the time-evolution of the device. The set of possible observations of the device is the set of our N2 logic variables. The number N is less than or equal to the number of accessible quantum states of the logic device. N2 is larger than the number of variables of interest for the physicochemical system that is emulated

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Conclusion