A Visible Light Photon Counter (VLPC) is a

photon counting Photon counting is a technique in which individual photons are counted using a single-photon detector (SPD). A single-photon detector emits a pulse of signal for each detected photon. The counting efficiency is determined by the quantum efficienc ...

photodetector Photodetectors, also called photosensors, are devices that detect light or other forms of electromagnetic radiation and convert it into an electrical signal. They are essential in a wide range of applications, from digital imaging and optical ...

based on impurity-band conduction in

arsenic Arsenic is a chemical element; it has Symbol (chemistry), symbol As and atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and antimony. Arsenic is not ...

- doped silicon. They have high

quantum efficiency The term quantum efficiency (QE) may apply to incident photon to converted electron (IPCE) ratio of a photosensitive device, or it may refer to the TMR effect of a magnetic tunnel junction. This article deals with the term as a measurement of ...

and are able to detect single

photon A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are massless particles that can ...

s in the visible range of the electromagnetic spectrum. The ability to count the exact number of photons detected is extremely important for

quantum key distribution Quantum key distribution (QKD) is a secure communication method that implements a cryptographic protocol involving components of quantum mechanics. It enables two parties to produce a shared random secret key known only to them, which then can b ...

. Rockwell International's Science Center had previously announced the "Solid-State Photomultiplier" (SSPM), a wide-band (0.4–28 μm) detector.M.D. Petroff, M.G. Stapelbroek and W.A. Kleinhans: "Detection of Individual 0.4–28 μm Wavelength Photons via Impurity‐Impact Ionization in a Solid‐State Photomultiplier" ''Applied Physics Letters'' 51(6) pp.406-408 (1987) In the late 1980s a collaboration – initially consisting of Rockwell and

UCLA The University of California, Los Angeles (UCLA) is a public land-grant research university in Los Angeles, California, United States. Its academic roots were established in 1881 as a normal school then known as the southern branch of the C ...

– began developing scintillating-fiber particle trackers for use at the

Superconducting Super Collider The Superconducting Super Collider (SSC), nicknamed Desertron, was a particle accelerator complex under construction from 1991 to 1993 near Waxahachie, Texas, United States. Its planned ring circumference was with an energy of 20 TeV per proto ...

,M.D. Petroff and M. Atac: "High Energy Particle Tracking Using Scintillating Fibers and Solid State Photomultipliers" '' IEEE Transactions on Nuclear Science'' 36(1) pp.163-164. (1989)M. Atac: "Scintillating Fiber Tracking at High Luminosities using Visible Light Photon Counter Readout" pp.149-160 in ''Imaging Detectors In High Energy, Astroparticle And Medical Physics - Proceedings Of The UCLA International Conference'', J. Park (''ed.''), World Scientific Publishing (1996) based on a dedicated variant of the SSPM that came to be known as the Visible Light Photon Counter.B. Abbot ''et al.'': "Studies of Visible Light Photon Counters with Fast Preamplifiers" ''Conference Record of the 1991 IEEE Nuclear Science Symposium and Medical Imaging Conference'', Santa Fe, NM, USA, pp.369-373 (1991) The operating principles are similar to

APD APD is an initialism that may refer to: Medicine * Afferent pupillary defect * Acid Peptic Diseases * Ambulatory Peritoneal Dialysis * Pamidronic acid, also known as aminohydroxypropylidene bisphosphonate * Antipsychotic Drugs * Auditory proces ...

s but based on impurity-band conduction. The devices are made from

- doped silicon and have an impurity band 50 meV below the

conduction band In solid-state physics, the valence band and conduction band are the bands closest to the Fermi level, and thus determine the electrical conductivity of the solid. In nonmetals, the valence band is the highest range of electron energies in ...

, resulting in a

gain Gain or GAIN may refer to: Science and technology * Gain (electronics), an electronics and signal processing term * Antenna gain * Gain (laser), the amplification involved in laser emission * Gain (projection screens) * Information gain in de ...

of to at a

reverse bias Reverse or reversing may refer to: Arts and media * ''Reverse'' (Eldritch album), 2001 * ''Reverse'' (2009 film), a Polish comedy-drama film * ''Reverse'' (2019 film), an Iranian crime-drama film * ''Reverse'' (Morandi album), 2005 * ''Reverse'' ...

of only a few volts (e.g. 7 V).In contrast, SPADs require a high

voltage and consequent quenching of the output current. The narrow

bandgap In solid-state physics and solid-state chemistry, a band gap, also called a bandgap or energy gap, is an energy range in a solid where no electronic states exist. In graphs of the electronic band structure of solids, the band gap refers to the ...

reduces gain dispersion, resulting in a uniform response to each photon, and hence the output pulse height is proportional to the number of incident photons. VLPCs must operate at

cryogenic In physics, cryogenics is the production and behaviour of materials at very low temperatures. The 13th International Institute of Refrigeration's (IIR) International Congress of Refrigeration (held in Washington, DC in 1971) endorsed a univers ...

temperatures (6–10 K).M.D. Petroff and M.G. Stapelbroek: "Photon-Counting Solid-State Photomultiplier" ''IEEE Transactions on Nuclear Science'' 36(1) pp.158-162. . (1989) They have a quantum efficiency of 85% at 565 nm and a

temporal resolution Temporal resolution (TR) refers to the discrete resolution of a measurement with respect to time. It is defined as the amount of time needed to revisit and acquire data for exactly the same location. When applied to remote sensing, this amount of ...

of several

nanoseconds A nanosecond (ns) is a unit of time in the International System of Units (SI) equal to one billionth of a second, that is, of a second, or seconds. The term combines the SI prefix ''nano-'' indicating a 1 billionth submultiple of an SI unit (e ...

. VLPCs have been used extensively in the central tracking detector of the

D0 experiment D, or d, is the fourth letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''dee'' (pronounced ), plural ''dees''. History Th ...

,D. Adams ''et al.'': "Performance of a Large Scale Scintillating Fiber Tracker Using VLPC Readout" ''IEEE Transactions on Nuclear Science'' 42(4) pp.401-406 (1995)D0 Collaboration: “The Upgraded D0 Detector” ''Nuclear Instruments and Methods'' A565 pp.463–537 (2006) and for

muon A muon ( ; from the Greek letter mu (μ) used to represent it) is an elementary particle similar to the electron, with an electric charge of −1 '' e'' and a spin of ''ħ'', but with a much greater mass. It is classified as a ...

beam-cooling studies for a muon collider (

MICE A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...

).M. Ellis ''et al.'', “The Design, Construction and Performance of the MICE Scintillating Fibre Trackers,” ''Nuclear Instruments and Methods'' A659 pp.136–153 (2011) They have also been evaluated for

quantum information science Quantum information science is a field that combines the principles of quantum mechanics with information theory to study the processing, analysis, and transmission of information. It covers both theoretical and experimental aspects of quantum phys ...

.K. McKay "''Development of the Visible Light Photon Counter for Applications in Quantum Information Science''" Dissertation, Duke University, http://hdl.handle.net/10161/4990 (2011)

Notes

References

{{Reflist Photodetectors Quantum cryptography Single-photon detectors