Daniel Istrati

Measurements of the dependence of the photon-number distribution on the number of modes in parametric down-conversion

Optical parametric down-conversion (PDC) is a central tool in quantum optics experiments. The number of collected down-converted modes greatly affects the quality of the produced photon state. We use Silicon Photomultiplier (SiPM) number-resolving detectors in order to observe the photon-number distribution of a PDC source, and show its dependence on the number of collected modes. Additionally, we show how the stimulated emission of photons and the partition of photons into several modes determine the overall photon number. We present a novel analytical model for the optical crosstalk effect in SiPM detectors, and use it to analyze the results.

Highly Directional Room-Temperature Single Photon Device

One of the most important challenges in modern quantum optical applications is the demonstration of efficient, scalable, on-chip single photon sources, which can operate at room temperature. In this paper we demonstrate a room-temperature single photon source based on a single colloidal nanocrystal quantum dot positioned inside a circular bulls-eye shaped hybrid metal-dielectric nanoantenna. Experimental results show that 20% of the photons are emitted into a very low numerical aperture (NA < 0.25), a 20-fold improvement over a free-standing quantum dot, and with a probability of more than 70% for a single photon emission. With an NA = 0.65 more than 35% of the single photon emission is collected. The single photon purity is limited only by emission from the metal, an obstacle that can be bypassed with careful design and fabrication. The concept presented here can be extended to many other types of quantum emitters. Such a device paves a promising route for a high purity, high efficiency, on-chip single photon source operating at room temperature.

Simulations of photon detection in silicon photomultiplier number-resolving detectors

Number-resolving single-photon detectors are essential for the implementation of numerous innovative quantum information schemes. While several number-discriminating techniques have previously been presented, the silicon photo-multiplier (SiPM) detector is a promising candidate owing to its rather simple integration in optical setups. On the other hand, the photon statistics obtained with the SiPM detector suffer from inaccuracies due to inherent distortions which are dependent on the geometrical properties of the SiPM. We simulated the detection process in an SiPM detector and studied these distortions. We used the results of the simulation to interpret the experimental data and to study the limits in which available models prevail.

Demonstration of a quantum error correction for enhanced sensitivity of photonic measurements

The sensitivity of classical and quantum sensing is impaired in a noisy environment. Thus, one of the main challenges facing sensing protocols is to reduce the noise while preserving the signal. State of the art quantum sensing protocols that rely on dynamical decoupling achieve this goal under the restriction of long noise correlation times. We implement a proof-of-principle experiment of a protocol to recover sensitivity by using an error correction for photonic systems that does not have this restriction. The protocol uses a protected entangled qubit to correct a single error. Our results show a recovery of about 87% of the sensitivity, independent of the noise rate.

Direct observation of the degree of correlations using photon-number-resolving detectors

Optical parametric down-conversion is a common source for the generation of non-classical correlated photonic states. Using a parametric down-conversion source and photon-number resolving detectors, we measure the two-mode photon-number distribution of up to 10 photons. By changing the heralded collection efficiency, we control the level of correlations between the two modes. Clear evidence for photon-number correlations are presented despite detector imperfections such as low detection efficiency and other distorting effects. Two criteria, derived directly from the raw data, are shown to be good measures for the degree of correlation. Additionally, using a fitting technique, we find a connection between the measured photon-number distribution and the degree of correlation of the reconstructed original two-mode state. These observations are only possible as a result of the detection of high photon number events.

Low intensity LiDAR using compressed sensing and a photon number resolving detector

LiDAR (laser based radar) systems are a major part of many new real-world interactive systems, one of the most notable being autonomous cars. The current market LiDAR systems are limited by detector sensitivity: when output power is at eye-safe levels, the range is limited. Long range operation also slows image acquisition as ight-time increases. We present an approach that combines a high sensitivity photon number resolving diode with machine learning and a micro-mechanical digital mirror device to achieve safe and fast long range 3D scanning.

Simple source for large linear cluster photonic states

The experimental realization of many-body entangled states is one of the main goals of quantum technology as these states are a key resource for quantum computation and quantum sensing. However, increasing the number of photons in an entangled state has been proved to be a painstakingly hard task. This is a result of the nondeterministic emission of current photon sources and the distinguishability between photons from different sources. Moreover, the generation rate and the complexity of the optical setups hinder scalability. Here we present a scheme that is compact, requires a very modest number of components, and avoids the distinguishability issues by using only one single-photon source. States of any number of photons are generated with the same configuration, with no need for increasing the optical setup. The basic operation of this scheme is experimentally demonstrated, and its sensitivity to imperfections is considered.

Experimental super resolved phase measurements at the shot noise limit

Using photon-number resolving detectors, we directly measure the parity of coherent states in a Mach-Zehnder interferometer. Phases are super resolved by a factor of 150 and shot noise limited measurements are demonstrated with 200 photons.

Direct measurements of the non-classicality degree in photon-number correlations

Using photon-number resolving detectors, we directly measure the two-mode photon-number distribution of parametric down-conversion for different degrees of correlation. We present two quantitative measures for the degree of non-classicality.

The Dependence of the Photon-number Distribution of Parametric Down-conversion on the Number of Collected Modes

The dependence of the photon-number distribution from parametric down-conversion on the number of collected modes is directly measured using Silicon Photo-Multiplier number-resolving detectors. Measurements are analyzed using a novel crosstalk model.