Yoshitaka Taguchi

Balanced detection is a popular method to cancel out the effect of laser intensity noise in optical measurements and spectroscopy. However, the signal-to-noise ratio (SNR) that can be achieved with balanced detection is constrained by the standard quantum limit (SQL). Here, we propose quantum-enhanced balanced detection (QBD), which allows us to improve the SNR beyond the SQL to realize ultrasensitive transmission measurement. In QBD, squeezed vacuum is injected to one of the input ports of a be

Programmable unitary photonic devices are emerging as promising tools to implement unitary transformation for quantum information processing, machine learning, and optical communication. These devices typically use a rectangular mesh of Mach-Zehnder interferometers, which has a clear mathematical structure and can be configured deterministically. However, this mesh architecture is sensitive to fabrication errors, and the correction techniques are still under investigation. In contrast, the multi

The pulsed squeezed state of light is expected to enhance the sensitivity of optical measurements using optical pulses. To achieve a high squeezing level, it is crucial to explore its limiting factors. In this study, we analyze the pulsed squeezed vacuum detected with picosecond pulses to explore two critical factors that limit the achievable squeezing level. First, we investigate the effect of the frequency chirp of local oscillator (LO) pulses and show that there exists an upper bound of the c

A 67-year-old woman was admitted to our hospital with confusion and asterixis on January 23, 1994. She had had the same symptoms repeatedly. On admission she was disorientated, and had slurred speech and asterixis. Laboratory data showed hyperammonemia (84 micrograms/dl) with a poor ICG hepatic clearance (ICG15min = 32%), although hepatic failure did not exist. Abdominal ultrasonography, CT scan and liver biopsy showed no evidence of cirrhosis. Celiac arteriography revealed a large shunt vessel

Programmable unitary converters are powerful tools for realizing unitary transformations, advancing the fields of computing and communication. The accuracy of these unitary transformations is crucial for maintaining high fidelity in such applications. However, various physical artifacts can impair the accuracy of the synthesized transformations. A commonly employed approach uses the system’s gradient to restore accuracy. Matrix norm is used to define error between matrices, and minimization of t

Abstract We numerically analyze an optical intensity modulator operating at a mid-infrared (MIR) wavelength based on a Ge/Si hybrid metal-oxide-semiconductor (MOS) capacitor formed by bonding a thin Ge membrane on a Si layer. Owing to the large free-carrier absorption of accumulated holes at the Ge MOS interface, the proposed optical modulator is predicted to exhibit efficient absorption modulation of >15 dB mm −1 with a 2 V amplitude of a gate voltage at a wide MIR spectrum from 2 to 7 μ m.

We propose a method for detecting phase mismatching by using an optical sideband, which imprints a phase shift on the pump light. By measuring this phase shift, phase mismatching can be detected for feedback control.

Requirement of mode mixers in optical unitary converters based on multi-plane light conversion is examined. The “entropy” of each mixer, which describes the degree of mixing, is revealed to be crucial in determining the performance.

We propose a method for detecting phase mismatching by using an optical sideband, which imprints a phase shift on the pump light. By measuring this phase shift, phase mismatching can be detected for feedback control.

Optical computing is emerging as a promising platform for energy-efficient, high-throughput hardware in deep learning. A key challenge lies in the realization of optical matrix-vector multiplication, which often requires $O(N^2)$ phase shifters for exact synthesis of $N \times N$ matrices, limiting scalability. In this study, we propose an approximate matrix realization method using multi-plane light conversion (MPLC) that reduces both the system size and the number of phase shifters while maint