130 research outputs found
Gaussian Optical Ising Machines
It has recently been shown that optical parametric oscillator (OPO) Ising
machines, consisting of coupled optical pulses circulating in a cavity with
parametric gain, can be used to probabilistically find low-energy states of
Ising spin systems. In this work, we study optical Ising machines that operate
under simplified Gaussian dynamics. We show that these dynamics are sufficient
for reaching probabilities of success comparable to previous work. Based on
this result, we propose modified optical Ising machines with simpler designs
that do not use parametric gain yet achieve similar performance, thus
suggesting a route to building much larger systems.Comment: 6 page
Quantum interference enables constant-time quantum information processing
Science, medicine and engineering demand efficient information processing. It is a long-standing goal to use quantum mechanics to significantly improve such computations. The processing routinely involves examining data as a function of complementary variables, e.g., time and frequency. This is done by the Fourier transform approximations which accurately compute inputs of samples in steps. In the quantum domain, an analogous process exists, namely a Fourier transform of quantum amplitudes, which requires exponentially fewer quantum gates. Here, we report a quantum fractional Kravchuk-Fourier transform, a related process suited to finite string processing. Unlike previous demonstrations, our architecture involves only one gate, resulting in constant-time processing of quantum information. The gate exploits a generalized Hong--Ou--Mandel effect, the basis for quantum-photonic information applications. We perform a proof-of-concept experiment by creation of large photon number states, interfering them on a beam splitter and using photon-counting detection. Existing quantum technologies may scale it up towards diverse applications
Tomography and state reconstruction with superconducting single-photon detectors
We perform quantum state reconstruction of coherent and thermal states with a
detector which has an enhanced multiphoton response. The detector is based on
superconducting nanowires, where the bias current sets the dependence of the
click probability on the photon number; this bias current is used as tuning
parameter in the state reconstruction. The nonlinear response makes our
nanowire-based detector superior to the linear detectors that are
conventionally used for quantum state reconstruction.Comment: revision of intro compared to V
Tomography and state reconstruction with superconducting single-photon detectors Citation for published version (APA)
- …