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Quantum interference enables constant-time quantum information processing



Thomas Gerrits, Sae Woo Nam, Adriana E. Lita, M. Stobinska, A. Buraczewski, M. Moore, W.R. Clements, J.J. Renema, W.S. Kolthammer, A. Eckstein, I.A. Walmsley


It is an open question how fast information processing can be performed and whether quantum effects can speed up the best existing solutions. Signal extraction, analysis, and compression in diagnostics, astronomy, chemistry, and broadcasting build on the discrete Fourier transform. It is implemented with the fast Fourier transform (FFT) algorithm that assumes a periodic input of specific lengths, which rarely holds true. A lesser-known transform, the Kravchuk-Fourier (KT), allows one to operate on finite strings of arbitrary length. It is of high demand in digital image processing and computer vision but features a prohibitive runtime. Here, we report a one-step computation of a fractional quantum KT. The quantum d-nary (qudit) architecture we use comprises only one gate and offers processing time independent of the input size. The gate may use a multiphoton Hong-Ou-Mandel effect. Existing quantum technologies may scale it up toward diverse applications.
Science Advances


quantum information processing, large photon number states, Kravchuk-Fourier transform


Gerrits, T. , Nam, S. , Lita, A. , Stobinska, M. , Buraczewski, A. , Moore, M. , Clements, W. , Renema, J. , Kolthammer, W. , Eckstein, A. and Walmsley, I. (2019), Quantum interference enables constant-time quantum information processing, Science Advances, [online], (Accessed July 21, 2024)


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Created July 19, 2019, Updated July 30, 2019