Unconditional measurement-based quantum computation with optomechanical continuous variables

Abstract

Universal quantum computation encoded over continuous variables can be achieved via Gaussian measurements acting on entangled non-Gaussian states. However, due to the weakness of available nonlinearities, generally these states can only be prepared conditionally, potentially with low probability. Here we show how universal quantum computation could be implemented unconditionally using an integrated platform able to sustain both linear and quadratic optomechanical-like interactions. Specifically, considering cavity opto-and electromechanical systems, we propose a realization of a driven-dissipative dynamics that deterministically prepares the required non-Gaussian cluster states-entangled squeezed states of multiple mechanical oscillators suitably interspersed with cubic-phase states. We next demonstrate how arbitrary Gaussian measurements on the cluster nodes can be performed by continuously monitoring the output cavity field. Finally, the feasibility requirements of this approach are analyzed in detail, suggesting that its building blocks are within reach of current technology.

Deterministic Gaussian conversion protocols for non-Gaussian single-mode resources

“…where we refer to the parameter c as the cubicity. Due to its fundamental role in quantum computation over continuous variables, various theoretical proposals have been put forward to generate such a state [10,17,35,[49][50][51][52][53][54][55][56][57][58], and recently a cubic-phase state was implemented experimentally in microvawe cavities [41]. To chose relevant parameters, we use the Wigner logarithmic negativity [31,32] as a guide, such that the negativity of our target cubic-phase state is comparable to the one of the other states investigated in this work.…”

“…In the context of quantum information science, continuousvariable (CV) quantum systems [1,2] are constituted of indistinguishable bosons that can be prepared, manipulated, and measured in order to implement relevant information processing protocols. They stand at the forefront of quantum technologies and, more recently, they have gained prominence in the context of quantum computation [3,4] over a variety of physical platforms, such as optical [5] and microwave radiation [6][7][8][9][10], trapped ions [11,12], opto-mechanical systems [13][14][15][16][17], atomic ensembles [18][19][20][21], and hybrid systems [22].…”

Generation of stable Gaussian cluster states in optomechanical systems with multifrequency drives

“…These investigations have been spurred by a number of theoretical proposals predicting many novel, interesting collective dynamics [30][31][32][33], including non-reciprocal transport [34,35], enhanced quantum sensing [36], quantum many-body effects [37][38][39][40][41][42], non-linear processes [43][44][45][46][47][48], and mechanical entanglement [42,[49][50][51][52][53][54][55][56][57]. Multimode optomechanics has also been suggested as a platform for quantum information processing and computation [55,[58][59][60]. Therefore, it is important to assess the requirements for achieving full control of the mechanical dynamics in such systems.…”

Trapping microparticles in a structured dark focus

“…-Light exerts forces upon matter [1]. As shown by Arthur Ashkin [2], these forces can be used to create stable traps for nano-and microscopic dielectric particles, with a myriad of applications from fundamental physics [3][4][5][6][7][8] to metrology [9,10], quantum information [11,12] and biology [13][14][15]. When the refractive index of the particle's material is larger than that of its surrounding medium, optical forces attract the object towards high intensities of light.…”