arXiv subjects

Fumihiko Kannari

Publications and source records attributed to Fumihiko Kannari.

4 recordsLinked to original sources

arXiv2024

Programmable Quantum Linear Interference with Pulse Shaping of Quantum Light

In this paper, we propose a novel method for interfering frequency-multiplexed photonic quantum states without the use of optical nonlinear effects, and experimentally demonstrate this technique via frequency-domain Hong-Ou-Mandel (HOM) interference. By cascading the generation of quantum states onto arbitrary orthogonal modes, we can induce interference across any desired frequency mode. Following the generation of quantum states onto the frequency modes, performing measurements in independent frequency bands enables the realisation of a frequency-domain linear optical circuit analogous to linear interference in the spatial domain. We successfully demonstrated programmable quantum interference by controlling the spectral mode functions and measurement bases. Our method offers a new approach to harness the full potential of light's temporal-frequency degrees of freedom, providing a path towards scalable and programmable photonic quantum computing architectures without the need for optical nonlinearities or spatial-mode beam splitters.

quant-ph↗

arXiv2024

Multimode Quantum Correlations in Supercontinuum Pulses

Suprecontinuum (SC) light contains complex spectral noise structure and its accurate characterization is important for fundamental understanding of its physics as well as for its applications. Several experimental and theoretical noise characterizations have been performed so far. However, none of them takes into account the quantum mechanical properties. Here, we demonstrate experimental characterisation of quantum noise and its spectral correlations formed in the SC light generated from a photonic crystal fiber. Moreover, by applying an appropriate basis transformation to these correlations, we demonstrate that the SC noise amplitude can be squeezed below the shot-noise limit in some bases, even in the presence of excessively large nonlinearities.

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arXiv2006

7 dB quadrature squeezing at 860 nm with periodically-poled KTiOPO4

We observed -7.2 dB quadrature squeezing at 860 nm by using a sub-threshold continuous-wave pumped optical parametric oscillator with a periodically-poled KTiOPO4 crystal as a nonlinear optical medium. The squeezing level was measured with the phase of homodyne detection locked at the quadrature. The blue light induced infrared absorption was not observed in the experiment.

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arXiv2006

Practical purification scheme for decohered coherent-state superpositions via partial homodyne detection

We present a simple protocol to purify a coherent-state superposition that has undergone a linear lossy channel. The scheme constitutes only a single beam splitter and a homodyne detector, and thus is experimentally feasible. In practice, a superposition of coherent states is transformed into a classical mixture of coherent states by linear loss, which is usually the dominant decoherence mechanism in optical systems. We also address the possibility of producing a larger amplitude superposition state from decohered states, and show that in most cases the decoherence of the states are amplified along with the amplitude.

quant-ph↗