High efficiency single-photon detection resides at the heart of many quantum information applications. Our efforts towards high efficiency, fast single photon detectors, and their range of applications and impacts in quantum optics will be discussed.
We develop quantum devices for the generation, manipulation and detection of light at the single photon level. Quantum dot devices allow for the generation of single and entangled photons at various frequencies including telecom wavelengths. We also develop single photon detectors with high efficiency based on NbTIN superconducting nanostructures, low noise and high time resolution to enable a range of applications including quantum communication, quantum sensing and integrated photonics. To allow for complex systems, integrated quantum optics circuits where we combine quantum sources and superconducting detectors are under development.
In this talk, I will present the latest results in superconducting single-photon detectors. Superconducting wires have remarkable sensitivity to single-photons and are a reliable and high-performance technology with significant impact on the quantum information research community. However, increasingly applications as diverse as detection of high-energy particles and searches for dark matter are being pursued. Finally, research on these nanowires has permitted their use for basic electronics circuits such as comparators, shift registers, and counters. We will review these and other topics surrounding the development of nanowire single-photon detectors.
Superconducting single-photon detectors can detect photons from the UV to the infrared with quantum efficiencies above 90% and greater than MHz count rates. They consist of narrow, thin wires of superconductor biased near their critical current. When these wires absorb a photon, part of the wire stops superconducting and becomes resistive. This transition and sudden jump in resistance is what enables the detection of the photon. Over the past two decades, these devices have matured greatly as a technology and have found many applications ranging from quantum optics to astronomy. However, there are still multiple theories of the dominant mechanism behind these devices. Recently proposed theories suggest a more complicated but potentially more powerful detection mechanism, and experiments are only recently starting to demonstrate this effect and its potential applications. In this research, the capability to fabricate these intricate devices was developed. This requires high-quality deposition of the superconductors, precise machining of the devices with electron beam lithography, and accurate etching of the films. Many parts of the process have been characterized. Additionally, two new directions are being explored. The first attempts to exploit the recently proposed detection mechanism to make detectors with much wider wires, leading to faster detection rates. The second is the fabrication of superconducting single-photon detectors directly onto optical fibers, eliminating the need for complicated coupling structures and alignment of the detector with the fiber.
In the last decade,more and more quantum information applications such as quantum key distribution have been extensively demonstrated.These emerging applications place rigorous demands on detector performance such as detection efficiency,intrinsic photon number resolving ability etc.that go beyond the capabilities of traditional single-photon detectors composed of either photomultiplier tubes(PMTs) or avalanche photodiodes(APDs).Fortunately,several new types of cryogenic detectors such as superconducting transition edge sensor(TES),superconducting nanowire single photon detector(SNSPD),and quantum-dot based single photon detector(QD SPD)have been realized recently.Here we review all kinds of single photon detector technologies at the present time. Advantages,disadvantages,and potential improvement of these techniques for quantum information applications are also discussed.