Photon number resolving in geiger mode avalanche photodiode photon counters

Abstract

The paper reports on research and development in the field of avalanche photodiodes operated as photon counters in a Geiger mode. A technique has been developed and tested that permits estimation of the photon number involved in a detection process. It can be applied in a time correlated photon counting experiment simultaneously with original required time interval estimation. A time walk compensation circuit provides uniform electrical pulses, and the time interval between them is related to the number of photons detected. Employing a picosecond event timing device, the photon number can be estimated within the dynamic range 1–1000 photons with resolution better than a factor of three.     

Evolution and prospects for single-photon avalanche diodes and quenching circuits

Abstract

The evolution of solid-state avalanche detectors of single optical photons is outlined and the issues for further progress are discussed. Physical phenomena that underlay the operation of the single-photon avalanche diodes (SPAD) and determine the performance are considered and their role is assessed (detection efficiency; dark-counting rate; afterpulsing; photon timing resolution; etc.). The main technological issues that hamper the development of detectors with wide sensitive area and of array detectors with high filling factor are illustrated. Silicon SPADs are the main focus of attention; infrared-sensitive SPADs in germanium and in compound semiconductors are also dealt with. The role of the active-quenching circuits (AQC) is assessed and the evolution is outlined up to integrated AQCs, which offer the prospect of monolithic integration of complete photon counter instruments.     

Ti/Au TES to Discriminate Single Photons

Single photon detectors are fundamental devices in several scientific fields, like in optical science and technology. We introduce the state of the art of Transition Edge Sensors, developed and characterized at INRIM, to detect photons from optical to near-infrared wavelength range (406–1570?nm). Both the capability to resolve up to 29 incident photons in a single pulse and to discriminate up to 2 photons with an energy resolution of 0.18?eV have been reached.     

Recent progress on cooled avalanche photodiodes for single photon detection

Abstract

Recent results on the properties of cooled avalanche photodiodes for single photon detection are presented. Results from Hamamatsu silicon photodiodes, originally developed as radiation-hard photodetectors for high energy physics experiments, are extremely encouraging. Gains of approximately 10,000 can be achieved with the APD operating in proportional mode. Together with a low noise amplifier they allow photon counting with extremely high efficiency and very low noise making cold APDs almost ideal single photon detectors. Operation of APDs in Geiger mode is also reported, together with measurements of detection efficiency and noise as function of operating voltage. Prospects and hopes for future work are briefly summarized.     

Squeezed Light

Abstract

In this paper we review the current state of progress in research on squeezed light. We discuss the basic theory of squeezing and the nature of quantum noise in optical fields. We examine various atomic sources of squeezed light and discuss phase-sensitive detectors of quantum noise including homodyne and heterodyne detectors. Various successful nonlinear optical methods for generating squeezed light are reviewed. We conclude with a discussion of the possible applications of squeezed light.     

14 MHz rate photon counting with room temperature InGaAs/InP avalanche photodiodes

Abstract

We have developed high speed gated-mode single-photon counters based on InGaAs/InP avalanche photodiodes for use at 1.55 μm wavelength. Operation at room temperature allows afterpulse probability to be below 0.2% for gate rates up to 14 MHz. We obtained optimum noise-equivalent power of 2.2 ×s; 10^?15 W Hz^?1/2 at 14% quantum efficiency with dark-count probability of 0.2%. We propose a metric (noise-equivalent power divided by gate frequency) for comparing high speed photon counters and show that for this metric our system outperforms previously reported counters at 1.55 μm wavelength. We demonstrate that for gate widths of a nanosecond or below, the differing amplitude distributions of dark versus light counts allow an optimal decision threshold to be set for a given bias voltage.     

Positron-electron pair spectrometry with selective mini-orange devices

Pair spectrometers have been developed with mini-orange filters and adaptedSi(Li) detectors. They have been employed in searches for resonant Bhabha scattering and viable axions. They are of implicit value for studies of pair creation with the high resolution of solid state detectors, with the high acceptance of mini-orange filters and with high specificity for recognition of e⁺e⁻ 1090 1568 V 3 pairs. The latter is due to the first-order magnetic focusing and can be further enhanced (optional) by observation of annihilation quanta after detection of a position. Special emphasis is devoted to a fourfold arrangement for Bhabha spectrometry, introducing coincident e⁺e⁻-pair observations with a central four-segmented Si(Li) counters in sideways positions for detection of correlated positrons.     

On Increasing the Resolution of Optical Receivers

Abstract

One approach for increasing the temporal resolution of optical receivers is discussed. It is based on a model of a photomultiplier with a set of resonators excited by secondary electrons together with retrieving algorithms. The resolution of such a system does not depend on the time-broadening of the secondary electron packets. In some cases, to increase the resolution it is not necessary to improve such parameters of the photomultiplier as time-broadening, jitter, etc., where the resolution of the photon detectors are defined with respect to single output video pulses.     

PARTICLE COUNTING OIL AND WATER EMULSIONS

ABSTRACT

Because of their speed and convenience, optical particle counters are widely used for particle size analysis of liquid samples. In some cases, both solid particles and emulsified water or oil may be present in a sample. Since emulsion droplets are counted as if they are solid particles, analysis and data interpretation for these samples are difficult. Until recently, no suitable method existed for distinguishing solid contaminants from emulsion droplets. This paper discusses a method which overcomes this limitation. Through the use of a surfactant-laden nonpolar dilution fluid, water is incorporated into reverse micelles too small to be seen by most optical particle counters. As a result, only solid contaminants are counted, and many problems associated with the analysis of emulsions are overcome. Results obtained from a wide range of oil and water emulsions are used to evaluate the merits and possible applications of the new technique.     

Liquid and solid organic photocathodes

We have investigated the possibility of creating photocathodes for gaseous detectors with a high sensitivity in the photon spectral region between 105 and 300 nm. Metal cathodes covered with liquid or solid organic layers, such as tetrakis (dimethylamine)ethylene (TMAE) and tetramethyl-p-phenylenediamine (TMPD) and solutions of these substances, were studied using two different experimental setups: a proportional wire chamber and a single-wire counter. There effects were observed. First, a thin film of absorbed vapours led to the efficiency of the metallic cathode being increased by more than one order of magnitude at photon wavelengths up to λ ≈ 400 nm. Secondly, a thick layer of liquid strongly increased the cathode efficiency Q for radiations of λ < 270 nm: e.g. with TMAE we obtained a yield of about 0.5%, for λ = 235 nm. Thirdly, we found that some solid layers, such as neopentane+TMAE, give a maximum efficiency Q ≈ 3% at λ = 235 nm. The quantum yields of liquid and solid photocathodes increase with increasing applied electric field. Some applications of the liquid and solid photocathodes are discussed.     

Nonlinear quantum optical computing via measurement

Abstract

We show how the measurement induced model of quantum computation proposed by Raussendorf and Briegel (2001, Phys. Rev. Letts., 86, 5188) can be adapted to a nonlinear optical interaction. This optical implementation requires a Kerr nonlinearity, a single photon source, a single photon detector and fast feed forward. Although nondeterministic optical quantum information proposals such as that suggested by KLM (2001, Nature, 409, 46) do not require a Kerr nonlinearity they do require complex reconfigurable optical networks. The proposal in this paper has the benefit of a single static optical layout with fixed device parameters, where the algorithm is defined by the final measurement procedure.     

Study of Photon Antibunching in the Vacuum Field Two-photon Jaynes-Cummings Model Without the Rotating-wave Approximation

Abstract

We have numerically investigated photon antibunching in the two-photon Jaynes-Cummings model without the rotating-wave approximation when the system is restricted to the following initial condition: the atom in the excited state and the field in the vacuum state. The influence of the detuning Δ on photon antibunching has also been discussed.     

Bragg curve spectroscopy in a 4π geometry

Ionization counters employing Bragg curve spectroscopy have been constructed for use in a 4π geometry. These detectors compare very favorably in terms of both energy and charge resolution with small solid angle devices. These detectors have a large dynamic range because they are backed by scintillation detectors, and are thus capable of detecting and identifying particles with energies from 1 MeV/nucleon up to 200 MeV/nucleon.     

Thermodynamic assessment and applications of Ti-V-N system

Abstract

Experimental Ti-V-N phase diagram data have been thermodynamically assessed and a consistent set of thermodynamic functions has been developed. Calculations have been performed to reveal some important features of the system. Problem areas in experimental data are indicated. The thermodynamic calculation is linked with limiting casesfor solid state diffusion kinetics. This is applied to a numerical simulation of ternary solidification processes of Ti-V-N alloys and to a discussion of the nitriding behaviour of Ti-V alloys.     

Heralded multiphoton GHZ-type polarization entanglement generation from parametric down-conversion sources

We propose a scheme to generate an N-photon GHZ-type polarization-entangled state from 2N ? 1 parametric down-conversion sources, by using only linear optical elements and projective measurements. Successful preparation is heralded by detecting 3N ? 2 photons with ideal number-resolving photon detectors.     

Dissipation and Amplification of Jaynes-Cummings Superposition States

Abstract

There have recently been several proposals for generation of optical superposition states in the resonant atom-field interaction and more practically in microwave cavities. In the present paper we study the influence of the vacuum reservoir on properties of the near-superposition state of the cavity field which is described by the Jaynes-Cummings model at one-half of the revival time. Instead of introducing the cavity loss from the first instance of the atom-field interaction we consider the cavity loss only after the near-superposition state is produced and after the atom leaves the cavity. We solve the corresponding master equation with the initial condition being the Jaynes-Cummings field at one-half of the revival time. We find that under the influence of the vacuum reservoir the photon number distribution of the superposition state we study exhibits certain asymmetry around the mean photon induced by the decay process. We show that an analogous effect can be seen when the Jaynes-Cummings superposition state is amplified. For a basic test of our approach we study the dissipation and amplification of Fock states.     

Determining the state of a single cavity mode from photon statistics

Abstract

We present various schemes for measuring the quantum state of a single mode of the electromagnetic field. These involve measuring the photon statistics for the mode before and after an interaction with either one or two two-level atoms. The photon statistics conditioned on the final state of the atoms, for two choices of the initial set of atomic states, along with the initial photon statistics, may be used to calculate the complete quantum state in a simple manner. Alternatively, when one atom is used, two unconditioned sets of photon statistics, each after interaction with a single atom in different initial states, along with the initial photon statistics may be used to calculate the initial state in a simple manner. When the cavity is allowed to interact with just one atom, only pure cavity states which do not contain zeros in the photon distribution may be reconstructed. When two atoms are used we may reconstruct pure states which do not contain adjacent zeros in the photon distribution. Coherent states and number states are among those that may be measured with one-atom interaction, and squeezed states and ?Schrödinger cats‘ are among those that may be measured with a two-atom interaction.     

Phonon Noise in Thin Metal Films in an Advanced Energy Down-Conversion Stage

We have identified an important, new source of line broadening in single photon detectors that work on the principle of absorption in a thin metal film. Phonon down-conversion noise arises through the loss of high energy phonons into the substrate during the initial photon energy down-conversion stage. Because of the relatively small number of phonons initially involved in this process, the loss rate is subject to large fluctuations due to the statistical nature of the energy exchange processes. We have modelled the phonon down-conversion noise that arises in the final stage of the down-conversion cascade, during which the deposited energy is converted into predominantly electronic excitations. At this stage of down-conversion in thin films the cascade phonon energy is sufficiently small that the escape interfaces are accessible for all phonons. Solving the system of coupled integral equations for the interacting electron and phonon systems, we have derived explicit expressions for the variance of the deposited energy. We have compared the results with other known noise contributions for the two foremost types of single optical photon detectors, based on superconducting tunnel junctions and transition edge sensors.      

Effective preparation of the N-dimension spin Greenberger–Horne–Zeilinger state with quantum dots embedded in microcavities

We propose a scheme for preparation of the N-dimension spin Greenberger–Horne–Zeilinger state by exploiting quantum dots (QDs) embedded in microcavities. Numerically analysed results show that with the spin-selective photon reflection from the cavity, we can complete the scheme assisted by one polarized photon with high fidelity and 100% successful probability in principle. Furthermore, the set-up is just composed of simple linear optical elements, delay lines and conventional photon detectors, which are feasible with existing experimental technology. Moreover, QDs have numerous admirable features in weak-coupling regime, which are practicable in realistic cavity quantum electrodynamics system shown by previous numerical simulations and experiments. Therefore, our scheme might be realized in near future.     

Measurement device independent quantum key distribution assisted by hybrid qubit

Abstract

Measurement device independent Quantum Key Distribution (MDI-QKD), is immune to all attacks on detection and achieve immense improvement with respect to quantum key distribution system security. However, Bell state measurement (BSM), the kernel processing in MDI-QKD, can only identify two of the four Bell states, which limits the efficiency of the protocol. In this paper, a modified MDI-QKD with hybrid qubit is proposed to provide a major step towards answering this question. The hybrid qubits, which are composed of single photon qubit qubits and coherent qubit, are sent to the quantum relay to perform parallel BSMs synchronously and bit flip can be easily operated to complete the whole key distribution process. The secure key rate can be improved with our modified protocol owing to the higher success probability of BSM, which is increased by adding the parity check of coherent qubit. Furthermore, though our protocol requires photon number resolving detectors, the BSM of coherent state could be instead implemented using squeezed state which makes our scheme practical with state-of-the-art devices.