Applications of Homodyne Detection Technique: Quantum Measurement of Continuous Variables

Ashish Kumar Patra, G Raghavan, Kanaka Raju P

Vitor Lucas O. Sena, Moisés Alves, Santiago Zamora +3 more

In this work, we analyze a semi-device-independent technique for quantum random number generation (QRNG) certification based on coherent detection. We consider a prepare-and-measure scenario, in which pure quantum states are prepared and sequentially measured using homodyne detection, a continuous-variable measurement, and evaluate dimension witness (DW) inequalities to certify quantum randomness. We extend the DW framework to this continuous-variable setting through phase-space binning optimization and demonstrate that symmetric binning maximizes DW violation across single-, double-, and triple-partition configurations. We additionally explore heterodyne (double homodyne) detection as a complementary coherent measurement; no witness violation is observed under this scheme for several discretization schemes. This work provides additional analysis to the study of certifiable QRNG based on homodyne detection, a mature and widely available technology with natural applicability in secure network communications.

Nicolai B. Grosse, Thomas Symul, Magdalena Stobińska +2 more

Photon anti-bunching, or the tendency of photons to be detected apart from one another, is characterized by the second-order coherence function which has previously been measured using discrete-variable (DV) single-photon counting methods. The authors theoretically propose and experimentally demonstrate a continuous-variable (CV) technique for measuring the second-order coherence of quantum states of light at sideband frequencies. The scheme is based on the original Hanbury-Brown-Twiss (HBT) intensity interferometer, but instead uses optical homodyne detection in each arm, to obtain the second-order coherence from a set of quadrature amplitude correlation measurements (each of which can be independently time-averaged).

T. Richter

Jiamin Li, Yuhong Liu, Nan Huo +4 more

The traditional method for measuring Einstein-Podolsky-Rosen-type continuous-variable quantum entanglement relies on balanced homodyne detections, which are sensitive to vacuum quantum noise coupled in through losses due to various factors such as detector quantum efficiency and mode mismatching between the detected field and the local oscillator. In this paper, we propose and analyze a measurement method, which is realized by assisting the balanced homodyne detections with a high-gain phase-sensitive parametric amplifier. The employment of the phase-sensitive amplifier helps us to tackle the vacuum quantum noise originating from detection losses. Moreover, because the high-gain phase-sensitive amplifier can couple two fields of different types, the proposed scheme can be used to reveal quantum entanglement between two fields of different types by using only one balanced homodyne detection. Furthermore, detailed analysis shows that in the multimode case, the proposed scheme is also advantageous over the traditional method. Such a measurement method should find wide applications in quantum information and quantum metrology involving measurement of continuous variables.

Tiphaine Kouadou, Elie Gozlan, Loïc Garcia +11 more

Homodyne detection is a phase-sensitive measurement technique, essential for the characterization of continuous-variable (CV)-encoded quantum states of light. It is a key component to the implementation of CV quantum-information protocols and benefits from operating, by design, at room temperature. However, performing high-speed quantum information processing remains a major challenge, as conventional homodyne detectors often fail to sustain pulsed operation at high repetition rates due to electronic limitations. We present wideband homodyne detectors operating at near-infrared (NIR) and telecom wavelengths, with optimized performance at repetition rates up to 150 MHz. We demonstrate their performance by resolving the pulse-by-pulse structure of squeezed states of light at telecom wavelengths while preserving their spectral multimode properties.