High-efficiency Photon Detector Research Articles

Itinerant Microwave Photon Detector.

The realization of a high-efficiency microwave single photon detector is a long-standing problem in the field of microwave quantum optics. Here, we propose a quantum nondemolition, high-efficiency photon detector that can readily be implemented in present state-of-the-art circuit quantum electrodynamics. This scheme works in a continuous fashion, gaining information about the photon arrival time as well as about its presence. The key insight that allows us to circumvent the usual limitations imposed by measurement backaction is the use of long-lived dark states in a small ensemble of inhomogeneous artificial atoms to increase the interaction time between the photon and the measurement device. Using realistic system parameters, we show that large detection fidelities are possible.

High quantum-efficiency photon-number-resolving detector for photonic on-chip information processing

The integrated optical circuit is a promising architecture for the realization of complex quantum optical states and information networks. One element that is required for many of these applications is a high-efficiency photon detector capable of photon-number discrimination. We present an integrated photonic system in the telecom band at 1550 nm based on UV-written silica-on-silicon waveguides and modified transition-edge sensors capable of number resolution and over 40 % efficiency. Exploiting the mode transmission failure of these devices, we multiplex three detectors in series to demonstrate a combined 79 % ± 2 % detection efficiency with a single pass, and 88 % ± 3 % at the operating wavelength of an on-chip terminal reflection grating. Furthermore, our optical measurements clearly demonstrate no significant unexplained loss in this system due to scattering or reflections. This waveguide and detector design therefore allows the placement of number-resolving single-photon detectors of predictable efficiency at arbitrary locations within a photonic circuit - a capability that offers great potential for many quantum optical applications.

Real-Time Detection of Single Molecules in Solution by Confocal Fluorescence Microscopy

We report real-time detection of single fluorescent molecules in solution with a simple technique that combines confocal microscopy, diffraction-limited laser excitation, and a high-efficiency photon detector. The probe volume, ∼5.0 x 10 -6 L, is defined latitudinally by optical diffraction and longitudinally by spherical aberration. With an unlimited excitation throughput and a low background level, this technique allows fluorescence detection of single rhodamine molecules with a signal-to-noise ratio of ∼10 in 1 ms, which approaches the theoretical limit set by fluorescence saturation. Real-time measurements at a speed of 500 000 data points/s yield single-molecule fluorescence records that not only show the actual transit time of a particular molecule across the probe volume but also contain characteristically long (∼50 μs) and short (∼4 μs) dark gaps. Random-walk simulations of single fluorescent molecules provide evidence that these long and short dark periods are caused mainly by boundary re-crossing motions of a single molecule at the probe volume periphery and by intersystem crossing into and out of the dark triplet state. We have also extended the use of confocal fluorescence microscopy to study individual, fluorescently tagged biomolecules, including deoxynucleotides, single-stranded primers, and double-stranded DNA. The achieved sensitivity permits dynamic structural studies of individual λ-phage DNA molecules labeled with intercalating fluorescent dyes ; the results reveal large-amplitude DNA structural fluctuations that occur on the millisecond time scale.

A high-efficiency photon detector for parallel acquisition of UV inverse photoemission spectroscopy

We describe an ultraviolet photon detector realized for parallel acquisition of eight inverse photoemission spectra in the isochromatic mode, at photon energies from 10 to 25 eV. This simple and reliable device is obtained by combining an array of eight channeltrons corresponding to the various photon energies of the spectral and a single Csl-coated photocathode.