Macroscopic quantum information processing using spin coherent states

Byrnes, Tim; Rosseau, Daniel; Khosla, Megha; Pyrkov, Alexey N.; Thomasen, Andreas; Mukai, Tetsuya; Koyama, Shinsuke; Abdelrahman, Ahmed; Ilo-Okeke, Ebubechukwu O.

doi:10.1016/j.optcom.2014.08.017

Cited by 65 publications

(69 citation statements)

References 44 publications

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“…While currently microwave and radio frequency pulses are conventionally used to obtain the desired superposition of magnetic sublevels, our approach could offer a faster and high fidelity alternative. Our method is also naturally suited to quantum information processing applications where spin coherent states are used for quantum memories [7,[12][13][14]50]. As optical laser pulses can be tightly focused, methods such as that described here would contribute to scalable atom chip configurations where there are multiple BEC on the same chip that are individually controlled.…”

Section: Discussionmentioning

confidence: 99%

“…For further discussions on this see Refs. [14,49]. The STIRAP procedure that we have presented has some free parameters which are available for optimization.…”

Section: A Model Including Spontaneous Emissionmentioning

confidence: 99%

“…Mach-Zender type interference of BECs in microgravity has also been realized in a particle drop experiment [10], where the BECs spatial splitting and recombination with resulting matter-wave interference has been observed. Visions for BECs investigate them as switches for nanomechanical devices [11] or as candidates for quantum computing [12][13][14][15]. Laser cooled atoms exhibit long coherence times [16], and as such they fulfill a key condition required of physical systems in quantum information related tasks [17,18].…”

Section: Introductionmentioning

confidence: 99%

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Ultrafast coherent control of spinor Bose-Einstein condensates using stimulated Raman adiabatic passage

2016

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We propose the use of stimulated Raman adiabatic passage (STIRAP) to offer a fast high fidelity method of performing SU(2) rotations on spinor Bose Einstein condensates (BEC). Past demonstrations of BEC optical control suffer from difficulties arising from collective enhancement of spontaneous emission and inefficient two-photon transitions originating from selection rules. We present here a novel scheme which allows for arbitrary coherent rotations of two-component BECs while overcoming these issues. Numerical tests of the method show that for BECs of 87 Rb with up to 10 4 atoms and gate times of 1 µs, decoherence due to spontaneous emission can be suppressed to negligible values.

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Section: Discussionmentioning

confidence: 99%

“…For further discussions on this see Refs. [14,49]. The STIRAP procedure that we have presented has some free parameters which are available for optimization.…”

Section: A Model Including Spontaneous Emissionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ultrafast coherent control of spinor Bose-Einstein condensates using stimulated Raman adiabatic passage

2016

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“…An equivalent approach involves using total spin operators as quasibosonic variables to implement CV [12,13]. Recently, a third alternative to these paradigms has emerged [14,15], having characteristics common to both. The scheme, which we call ensemble quantum computation (EQC), stores quantum information on ensembles of qubits and manipulates them using only products of total spin operators.…”

Section: Introductionmentioning

confidence: 99%

“…For these reasons, the mapping between qubit algorithms to EQC requires some analysis, and currently no general procedure exists to map between the two. Nevertheless, to date several algorithms have been shown to be mapped, incuding quantum teleportation [16,17] and Deutsch's algorithm [15].…”

Section: Introductionmentioning

confidence: 99%

Implementing the Deutsch-Jozsa algorithm with macroscopic ensembles

Semenenko

Byrnes

2016

Phys. Rev. A

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms PHYSICAL REVIEW A 93, 052302 (2016) Implementing the Deutsch-Jozsa algorithm with macroscopic ensembles Quantum computing implementations under consideration today typically deal with systems with microscopic degrees of freedom such as photons, ions, cold atoms, and superconducting circuits. The quantum information is stored typically in low-dimensional Hilbert spaces such as qubits, as quantum effects are strongest in such systems. It has, however, been demonstrated that quantum effects can be observed in mesoscopic and macroscopic systems, such as nanomechanical systems and gas ensembles. While few-qubit quantum information demonstrations have been performed with such macroscopic systems, a quantum algorithm showing exponential speedup over classical algorithms is yet to be shown. Here, we show that the Deutsch-Jozsa algorithm can be implemented with macroscopic ensembles. The encoding that we use avoids the detrimental effects of decoherence that normally plagues macroscopic implementations. We discuss two mapping procedures which can be chosen depending upon the constraints of the oracle and the experiment. Both methods have an exponential speedup over the classical case, and only require control of the ensembles at the level of the total spin of the ensembles. It is shown that both approaches reproduce the qubit Deutsch-Jozsa algorithm, and are robust under decoherence.

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Nontrivial Attractors of the Perturbed Nonlinear Schrödinger Equation: Applications to Associative Memory and Pattern Recognition

2019

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Computers are dynamical systems that carry out information processing through their change of state with time. For instance, neural networks such as Hopfield's associative memory are dissipative dynamical systems in a finite dimensional configuration space with attractors that represent stored patterns. In particular, dissipative dynamical systems with an infinite dimensional configuration space are of broad interest and have the possibility to store and restore complex and strongly distorted data structures. In this work, the nonlinear Schrödinger equation (NLSE) with a dissipative perturbation which creates a frictional force acting on soliton is considered. It is shown that the control of the perturbative term allows one to decrease the velocity of soliton to zero and conserve a positive value of its amplitude. The existence of such a frictional force would suggest that the perturbation makes the zero‐velocity solitonic solution of non‐zero amplitude into an attractor for all evolution trajectories whose initial conditions are moving solitons. This allows a way to store information in the infinite dimensional dynamical system governed by NLSE using principles which are completely analogous to that of Hopfield's associative memory. This approach can be realized with solitons in Bose–Einstein condensates and nonlinear optical systems.

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Macroscopic quantum information processing using spin coherent states

Cited by 65 publications

References 44 publications

Ultrafast coherent control of spinor Bose-Einstein condensates using stimulated Raman adiabatic passage

Ultrafast coherent control of spinor Bose-Einstein condensates using stimulated Raman adiabatic passage

Implementing the Deutsch-Jozsa algorithm with macroscopic ensembles

Nontrivial Attractors of the Perturbed Nonlinear Schrödinger Equation: Applications to Associative Memory and Pattern Recognition

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