Coherent optical computers

Mario Vretenar, Ben Kassenberg, Klaas‐Jan Gorter +2 more

S. H. Lee

Rupert C. D. Young, Philip M. Birch, Chris R. Chatwin

Previously we have examined the similarities of the quantum Fourier transform to the classical coherent optical implementation of the Fourier transform (R. Young et al, Proc SPIE Vol 87480, 874806-1, -11). In this paper, we further consider how superposition states can be generated on coherent optical wave fronts, potentially allowing coherent optical processing hardware architectures to be extended into the quantum computing regime. In particular, we propose placing the pixels of a Spatial Light Modulator (SLM) individually in a binary superposition state and illuminating them with a coherent wave front from a conventional (but low intensity) laser source in order to make a so-called ‘interaction free’ measurement. In this way, the quantum object, i.e. the individual pixels of the SLM in their superposition states, and the illuminating wavefront would become entangled. We show that if this were possible, it would allow the extension of coherent processing architectures into the quantum computing regime and we give an example of such a processor configured to recover one of a known set of images encrypted using the well-known coherent optical processing technique of employing a random Fourier plane phase encryption mask which classically requires knowledge of the corresponding phase conjugate key to decrypt the image. A quantum optical computer would allow interrogation of all possible phase masks in parallel and so immediate decryption.

A. Kozma

Yanchen JIANG, Tiejun Wang

Coherent light computing is a specialized computational method based on quantum optics and non von Neumann frameworks, which is expected to break through the bottleneck of computational performance and power consumption in the post Moore era. The core idea of coherent light calculation is based on the principle of minimum gain. By gradually increasing the intensity of the pump light in the degenerate optical parametric oscillator, the lowest energy ground state mode in the oscillator is excited, thus completing a process similar to physical annealing. This annealing process can be used to solve combinatorial optimization problems and has advantages such as fast computation speed, high solution quality, and low power consumption. Coherent optical computers, also known as Coherent Ising Machines, can be used for fast and high-quality solutions to problems such as traffic flow allocation, industrial resource scheduling, and financial investment portfolios. They are an important research direction in quantum computing hardware. This paper, as the second part of the “Advanced Computational Power Technology” topic, introduces the basic principles, historical development and experimental systems of coherent optical computing and coherent Ising machines. This paper not only serves as a general introduction to the future field of computing technology, but the PPT given in the appendix also serves as a useful supplement to the “Quantum Physics” chapter in university physics and other courses.

Philip Hemmer, Alexey V. Turukhin, M. S. Shahriar +1 more

Summary form only given. The use of optical Raman interactions to excite spin coherences in solids has numerous potential applications, ranging from low-power nonlinear optics to high-temperature spectral hole burning memories to solid-state quantum computing. The interest in Raman excitation lies in the fact that the spin coherences can be efficiently excited and manipulated using optical laser fields yet are weakly coupled to the environment and hence have the long coherence lifetimes needed for optical memories and quantum computing. The interest in nitrogen-vacancy (N-V) color centers in diamond is its large optical oscillator strength. For memory, a large oscillator strength is important for high temperature operation. For quantum computing, the high optical transition rate enables the higher gate speed and the larger number of quantum logic operations that can be performed within the spin coherence lifetime.