Showing papers in "Journal of Modern Optics in 2004"
TL;DR: In this article, the evolution of solid-state avalanche detectors of single optical photons is discussed and issues for further progress are discussed, and the main technological issues that hamper the development of detectors with wide sensitive area and of array detectors with high filling factor are illustrated.
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.
352 citations
TL;DR: In this article, a method of single photon detection of infrared (IR) photons at potentially higher efficiencies and lower noise than allowed by traditional IR band avalanche photodiodes (APDs) was proposed.
Abstract: We propose a method of single photon detection of infrared (IR) photons at potentially higher efficiencies and lower noise than allowed by traditional IR band avalanche photodiodes (APDs). By up-converting the photon from the IR, e.g. 1550 nm, to a visible wavelength in a nonlinear crystal, we can utilize the much higher efficiency of silicon APDs at these wavelengths. We have used a periodically poled lithium niobate (PPLN) crystal and a pulsed 1064 nm Nd:YAG laser to perform the up-conversion to a 631 nm photon. We observed conversion efficiencies as high as ∼ 80%, and demonstrated scaling down to the single photon level while maintaining a background of 3 ×s; 10−4 dark counts per count. We also propose a 2-crystal extension of this scheme, whereby orthogonal polarizations may be up-converted coherently, thus enabling complete quantum state transduction of arbitrary states.
230 citations
TL;DR: In this paper, the authors describe the construction of a time-multiplexed detector, which uses a pair of standard avalanche photodiodes operated in Geiger mode, for resolving any number of photons.
Abstract: Detectors that can resolve photon number are needed in many quantum information technologies. In order to be useful in quantum information processing, such detectors should be simple, easy to use, and be scalable to resolve any number of photons, as the application may require great portability such as in quantum cryptography. Here we describe the construction of a time-multiplexed detector, which uses a pair of standard avalanche photodiodes operated in Geiger mode. The detection technique is analysed theoretically and tested experimentally using a pulsed source of weak coherent light.
144 citations
TL;DR: InGaAs/InP avalanche photodiodes operated in the so-called Geiger mode currently represent the best solution to detect single-photon beyond 900nm as mentioned in this paper.
Abstract: InGaAs/InP avalanche photodiodes operated in the so-called Geiger mode currently represent the best solution to detect single-photon beyond 900nm. They cover the 1100–1650nm wavelength interval, which includes in particular the two windows used for optical communications (1310 and 1550nm). A detection efficiency at 1550nm of 10% with a dark count probability of 10−5 ns−1 is common, although significant variations can be encountered. At this efficiency, a FWHM temporal response of 300 ps can be achieved. Afterpulses caused by charges trapped by defects in the high field region of the junction constitute the main performance impairment phenomenon. They enhance the dark count probability and reduce out-of-gate detector blindness. These photon counting detectors can be used in optical time-domain reflectometry to improve the spatial resolution and reduce dead-zone effects. Quantum key distribution over metropolitan area networks also constitutes an important application.
122 citations
TL;DR: In this paper, the physics of four-photon states generated in spontaneous parametric down-conversion with a pulsed pump field were studied, where the coherence time of the photons t ph c is much shorter than the duration of the pump pulse Δt.
Abstract: We study the physics of four-photon states generated in spontaneous parametric down-conversion with a pulsed pump field. In the limit where the coherence time of the photons t ph c is much shorter than the duration of the pump pulse Δt, the four photons can be described as two independent pairs. In the opposite limit, the four photons are in a four-particle entangled state. Any intermediate case can be characterized by a single parameter χ, which is a function of t ph c Δt. We present a direct measurement of χ through a simple experimental set-up. The full theoretical analysis is also provided.
89 citations
TL;DR: In this article, a commercial avalanche photodiode and the circuitry needed to operate it as a single-photon detector (SPD) have been integrated onto a single PC board (PCB).
Abstract: A commercial avalanche photodiode (APD) and the circuitry needed to operate it as a single-photon detector (SPD) have been integrated onto a single PC board (PCB). At temperatures accessible with Peltier coolers (∼200–240 K), the PCB-SPD achieves high detection efficiency (DE) at 1308 and 1545 nm with low dark-count probability (e.g. ∼10−6/bias pulse at DE = 20%, 220 K), making it useful for quantum key distribution (QKD). The board generates fast bias pulses, cancels noise transients, amplifies the signals, and sends them to an on-board discriminator. A digital blanking circuit suppresses afterpulsing.
89 citations
TL;DR: In this article, the authors presented a new approach using a fiber-based femtosecond laser system producing 300 fs pulses with pulse energies of 0.6 μJ at 2 MHz repetition rate.
Abstract: Using tightly focused ultrashort laser pulses allows the direct writing of three-dimensional photonic structures in different glasses and also crystalline media. One of the main drawbacks of this technology is, however, the limited writing speed achieved so far. In this paper we shall review our recent advances in the direct writing of three-dimensional integrated-optical devices and discuss a new approach using a fibre-based femtosecond laser system producing 300 fs pulses with pulse energies of 0.6 μJ at 2 MHz repetition rate. Using this laser system we fabricated low-loss waveguides (less than 0.5 dBcm−1) at writing speeds of 100 mms−1 for the first time. The influence of the writing speed on the produced structures as well as their optical properties will be discussed in detail.
87 citations
TL;DR: In this article, Niobium-nitride, superconducting single-photon detectors (SSPDs) are used for ultrafast counting of near-infrared photons for secure quantum communications.
Abstract: The paper reports progress on the design and development of niobium-nitride, superconducting single-photon detectors (SSPDs) for ultrafast counting of near-infrared photons for secure quantum communications. The SSPDs operate in the quantum detection mode, based on photon-induced hotspot formation and subsequent appearance of a transient resistive barrier across an ultrathin and submicron-width superconducting stripe. The devices are fabricated from 3.5 nm thick NbN films and kept at cryogenic (liquid helium) temperatures inside a cryostat. The detector experimental quantum efficiency in the photon-counting mode reaches above 20% in the visible radiation range and up to 10% at the 1.3–1.55 μn infrared range. The dark counts are below 0.01 per second. The measured real-time counting rate is above 2 GHz and is limited by readout electronics (the intrinsic response time is below 30 ps). The SSPD jitter is below 18 ps, and the best-measured value of the noise-equivalent power (NEP) is 2 × 10−18 W/Hz1...
73 citations
TL;DR: In this article, the authors report on the limitations of using a spatial light modulator (SLM) within optical tweezers to produce both lateral and axial displacements.
Abstract: We report on the limitations of using a spatial light modulator (SLM) within optical tweezers to produce both lateral and axial displacements. We find that lateral displacements of optical traps are limited by the optical efficiency of the SLM, whereas the axial displacements are limited by the abberations of the objective lens. In addition, we show the SLM can be used for correcting abberations arising from trapping deep within the sample. The maximum possible lateral and axial displacements were 50 μm and 40 μm, respectively.
71 citations
TL;DR: In this article, the projections of the Umov-Poynting vector for a two-dimensional TE-polarized Bessel beam and a three-dimensional paraxial linearly polarized beam are derived.
Abstract: We show that imaging a non-diverging Bessel beam by a spherical lens leads to the generation of a diverging Bessel beam. Expressions for the projections of the Umov-Poynting vector for a two-dimensional TE-polarized Bessel beam and a three-dimensional paraxial linearly polarized Bessel beam are derived. A fifth-order Bessel beam is produced using a single optical element-a 16-level phase-only diffractive helical axicon fabricated using electron beam lithography. This beam was successfully used to trap and rotate 5-10 μm diameter yeast particles and polystyrene beads of diameter 5 μm.
69 citations
TL;DR: The properties of fields generated by diffractive phase-only optical elements that generate combinations of two angular harmonic fields with different harmonic indices in Fraunhofer and Fresnel regions are investigated theoretically and experimentally.
Abstract: The properties of fields generated by diffractive phase-only optical elements that generate combinations of two angular harmonic fields with different harmonic indices in Fraunhofer and Fresnel regions are investigated theoretically and experimentally Camomile shaped diffraction patterns are predicted and observed It is shown that multi-order diffractive phase elements can be used to both generate these beams and to identify the weights of different angular harmonics in a given incident laser beam
TL;DR: In this paper, it was shown that the atomic states can be described by wavefunctions calculated in the absence of an electromagnetic field when using the d · E (but not the p · A) form of the interaction Hamiltonian.
Abstract: The interaction of an atomic system with an externally applied electromagnetic field can be treated in the electric dipole approximation by means of either the minimal coupling (p · A) or direct coupling (d · E) Hamiltonian. It is shown that both methods lead to identical and unambiguous predictions for observable quantities as long as the atomic wavefunctions are transformed when used in the minimal-coupling formulation. The physical meaning of kinetic momentum is used to show that the atomic states must be described by wavefunctions calculated in the absence of an electromagnetic field when using the d · E (but not the p · A) form of the interaction Hamiltonian. When, however, observables are calculated using the common approximations of resonance atomic physics – the two-level approximation and the rotatingwave approximation – the two formulations can lead to measurably different results. This point is illustrated by calculating the induced polarization (and hence the refractive index) of an a...
TL;DR: In this article, the authors explore novel methods of detecting radiation from astrophysical sources by means of matter-wave interferometers (MIGOs), using atomic beams emanating from supersonic atomic sources that are further cooled and collimated by meansof optical molasses.
Abstract: A dynamical non-Euclidean spacetime geometry in general relativity theory implies the possibility of gravitational radiation. Here we explore novel methods of detecting such radiation from astrophysical sources by means of matter-wave interferometers (MIGOs), using atomic beams emanating from supersonic atomic sources that are further cooled and collimated by means of optical molasses. While the sensitivities of such MIGOs compare favorably with LIGO and LISA, the sizes of MIGOs can be orders of magnitude smaller, and their bandwidths wider. Using a pedagogical approach, we place this problem into the broader context of problems at the intersection of quantum mechanics with general relativity.
TL;DR: In this article, the second-harmonic generation (SHG) output signal within the 1.5-4.8 μm spectral range has significant spectral dependence, and a correlation of the SHG spectral maxima positions with spectral positions of anharmonic phonon frequencies confirms that the fifth-order steady-state process occurs due to cascading processes and IR-induced charge density non-centrosymmetry.
Abstract: Theoretically predicted and experimentally observed infraredinduced second-harmonic generation of glasses in the mid-infrared spectral region can be described by fifth-order nonlinear optical susceptibility. The effect is observed in the mid-IR region when the value of the electronic energy gap is comparable to the energies of actual phonons participating in the anharmonic (non-centrosymmetric) electron-phonon interactions. As subjects for investigation, chalcohalide Sb2Te2Se-BaF2-PbCl2 glasses were chosen. They are transparent, over a spectral range of 1.1–10.9 μm. The second-harmonic generation (SHG) output signal within the 1.5–4.8 μm spectral range has significant spectral dependence. Correlation of the SHG spectral maxima positions with spectral positions of anharmonic phonon frequencies confirms that the fifth-order steady-state process occurs due to cascading processes and IR-induced charge density non-centrosymmetry. A maximum value of the SHG is achieved at a pump-probe delay time of 18–...
TL;DR: In this article, a brief overview of single photon detector performance requirements for quantum cryptography applications is given with respect to restrictions necessary to secure the quantum key distribution channel InGaAs/InP avalanche photodiode performance is analyzed for single photon counting at 1550 nm.
Abstract: A brief overview is given of single photon detector performance requirements for quantum cryptography applications The analysis is made with respect to restrictions necessary to secure the quantum key distribution channel InGaAs/InP avalanche photodiode performance is analysed for single photon counting at 1550 nm Quantum efficiency, dark current and afterpulsing probability (for times up to 100μs after an initial avalanche) are studied in a wider temperature range than previously reported (0deg; C to –80deg;C) We show that photon counting is a bottle-neck in current quantum key distribution systems and provides the source for future performance improvement
TL;DR: In this article, the authors provide a broad outline of the requirements that should be met by components produced for a QIT industry, and identify electromagnetically induced transparency (EIT) as potentially key enabling science toward the goal of providing widely available few-qubit quantum information processing within the next decade.
Abstract: We provide a broad outline of the requirements that should be met by components produced for a Quantum Information Technology (QIT) industry, and we identify electromagnetically induced transparency (EIT) as potentially key enabling science toward the goal of providing widely available few-qubit quantum information processing within the next decade. As a concrete example, we build on earlier work and discuss the implementation of a two-photon controlled phase gate (and, briefly, a one-photon phase gate) using the approximate Kerr nonlinearity provided by EIT. In this paper, we rigorously analyze the dependence of the performance of these gates on atomic dephasing and field detuning and intensity, and we calculate the optimum parameters needed to apply a π phase shift in a gate of a given fidelity. Although high-fidelity gate operation will be difficult to achieve with realistic system dephasing rates, the moderate fidelities that we believe will be needed for few-qubit QIT seem much more obtainable.
TL;DR: An overview of the history of this technique is given and the paper reviews how to implement it in a practical lab setting as discussed by the authors. But, some of the sources of uncertainty in the technique and how they can be minimized and quantified are discussed.
Abstract: Correlated photons can be used to directly measure the detection efficiency of photon counting detectors without any ties to externally calibrated standards. An overview of the history of this technique is given and the paper reviews how to implement it in a practical lab setting. Some of the sources of uncertainty in the technique and how they can be minimized and quantified are discussed. The intent is to provide the information necessary to encourage the movement of this technique from the metrology lab into the general photon-counting detector community.
TL;DR: In this paper, a space-qualified silicon avalanche-photodiode (APD) based single-photon counting module (SPCM) was developed for the Geoscience Laser Altimeter System (GLAS) on board NASA's Ice, Cloud and Land Elevation Satellite (ICESat).
Abstract: A space-qualified silicon avalanche-photodiode (APD) based single-photon-counting-module (SPCM) was developed for the Geoscience Laser Altimeter System (GLAS) on board NASA's Ice, Cloud, and Land Elevation Satellite (ICESat). Numerous improvements were made over the commercially available SPCMs in both performance and reliability. The measured optoelectronic parameters include, 65% photon detection efficiency at the 532nm wavelength, 15–17 mega-counts per second (Mcps) maximum count rate and less than 200s−1 dark counts before exposure to space radiation.
TL;DR: In this paper, a simplified formula for the eikonal function in the curvilinear coordinates is derived, which is exemplified by the line-shaped and arc-shaped directivity diagrams.
Abstract: Diffractive optical elements to form one-parameter directivity diagrams are designed using the geometric optics. The field ray structure corresponding to the line-shaped directivity diagram is analyzed and curvilinear coordinates for calculating the eikonal are proposed. A new simplified formula for the eikonal function in the curvilinear coordinates is derived. The calculation of the eikonal function is exemplified by the line-shaped and arc-shaped directivity diagram.
TL;DR: In this article, a pair of B 0 ¯ B 0 mesons from �(4S) decay exhibit EPR type non-local particle-antiparticle (flavor) correlation, and it is possible to write down Bell Inequality (in the CHSH form: S � 2) to test the nonlocality assumption of EPR.
Abstract: A pair of B 0 ¯ B 0 mesons from �(4S) decay exhibit EPR type non-local particle-antiparticle (flavor) correlation. It is possible to write down Bell Inequality (in the CHSH form: S � 2) to test the nonlocality assumption of EPR. Using semileptonic B 0 decays of �(4S) at Belle experiment, a clear violation of Bell Inequality in particle-antiparticle correlation is observed: S = 2.725 ± 0.167stat ± 0.092syst
TL;DR: In this article, the authors present a new computation scheme for the integral expressions describing the contributions of single aberrations to the diffraction integral in the context of an extended Nijboer-Zernike approach.
Abstract: We present a new computation scheme for the integral expressions describing the contributions of single aberrations to the diffraction integral in the context of an extended Nijboer-Zernike approach. Such a scheme, in the form of a power series involving the defocus parameter with coefficients given explicitly in terms of Bessel functions and binomial coefficients, was presented recently by the authors with satisfactory results for small-to-medium-large defocus values. The new scheme amounts to systemizing the procedure proposed by Nijboer in which the appropriate linearization of products of Zernike polynomials is achieved by using certain results of the modern theory of orthogonal polynomials. It can be used to compute point-spread functions of general optical systems in the presence of arbitrary lens transmission and lens aberration functions and the scheme provides accurate data for any, small or large, defocus value and at any spatial point in one and the same format. The cases with high numerical aperture, requiring a vectorial approach, are equally well handled. The resulting infinite series expressions for these point-spread functions, involving products of Bessel functions, can be shown to be practically immune to loss of digits. In this respect, because of its virtually unlimited defocus range, the scheme is particularly valuable in replacing numerical Fourier transform methods when the defocused pupil functions require intolerably high sampling densities.
TL;DR: In this article, the current status of dynamical decoupling techniques in terms of required control resources and feasibility is discussed, based on recent advances in both improving the theoretical design and assessing the control performance for specific noise models.
Abstract: I address the current status of dynamical decoupling techniques in terms of required control resources and feasibility. Based on recent advances in both improving the theoretical design and assessing the control performance for specific noise models, I argue that significant progress may still be possible on the road of implementing decoupling under realistic constraints.
TL;DR: In this paper, the authors report on results of research and development in the field of solid state single photon detectors at the Czech Technical University in Prague over the last 20 years, including the development of avalanche photodiodes specifically designed for single photon counting devices based on various semiconductor materials.
Abstract: Solid state single photon detectors are receiving more and more attention in a number of areas of applied physics: optical sensors, communications, quantum cryptography, optical ranging and Lidar, time resolved spectroscopy, opaque media imaging and ballistic photon identification. This paper reports on results of research and development in the field of solid state single photon detectors at the Czech Technical University in Prague over the last 20 years. Avalanche photodiodes specifically designed for single photon counting devices have been developed based on various semiconductor materials: Si, Ge, GaP, GaAs and InGaAs. Electronic circuits for biasing, quenching and control of these detectors have been developed and optimized for different applications. The sensitivity of solid state photon counters spans from 0.1 nanometre X-rays up to 1800 nanometres in the near infrared region. Timing resolution of solid state photon counters as high as 50 picoseconds full width at a half maximum has been ...
TL;DR: In this paper, the oblique incidence of a He-Ne laser beam onto a phase-only diffractive optical element (DOE) that simultaneously produces several unimode different-order Bessel beams propagating at various angles with respect to the optical axis is studied theoretically and experimentally.
Abstract: The oblique incidence of a He-Ne laser beam onto a phase-only diffractive optical element (DOE) that simultaneously produces several unimode different-order Bessel beams propagating at various angles with respect to the optical axis is studied theoretically and experimentally. It is shown that, under obliquely incident illumination of a DOE that forms Bessel beams, the resulting astigmatic diffraction pattern can be used to unambiguously identify the direction of the Bessel beam's phase rotation and the order of the Bessel mode.
TL;DR: In this paper, the properties of a photodetector that has a number-resolving capability were studied and a non-photon number-discriminating detector was proposed to reconstruct the photon number distribution of the incident field even in the presence of dark counts.
Abstract: We study the properties of a photodetector that has a numberresolving capability In the absence of dark counts, due to its finite quantum efficiency, photodetection with such a detector can only eliminate the possibility that the incident field corresponds to a number of photons less than the detected photon number We show that such a non-photon number-discriminating detector, however, provides a useful tool in the reconstruction of the photon number distribution of the incident field even in the presence of dark counts
TL;DR: In this article, the authors derived the full solution of the coined quantum walk on a line by using a new approach based on the four "walk fields" which determined the dynamics of the walk.
Abstract: We analyse the solution of the coined quantum walk on a line. First, we derive the full solution, for arbitrary unitary transformations, by using a new approach based on the four ‘walk fields’ which we show determine the dynamics. The particular way of deriving the solution allows a rigorous derivation of a long wavelength approximation. This long wavelength approximation is useful as it provides an approximate analytical expression that captures the basics of the quantum walk and allows us to gain insight into the physics of the process.
TL;DR: In this article, the authors reported the results of characterization, simulation and optimization of a one-dimensional liquid crystal (LC) SLM, which has a large ratio between LC layer thickness and pixel pitch that results in a fringing field between pixels.
Abstract: Phase modulating spatial light modulators (SLMs) can be used to alter the shape of a laser wavefront to achieve a deflection or change in the shape of a laser beam. This paper reports the results of characterization, simulation and optimization of a one-dimensional liquid crystal (LC) SLM. The device has a large ratio between LC layer thickness and pixel pitch that results in a fringing field between pixels. In effect, the applied phase patterns will be lowpass filtered and the loss of high frequency components limits, for instance, the usable steering range. A method is presented where intensity measurements in the far field are used to determine how the phase modulation at the SLM is distorted. The inhomogeneous optical anisotropy of the device was determined by modelling the liquid crystal director distribution within the electrode-pixel structure. Finite-difference time-domain (FDTD) simulations were used to calculate the light propagation through the LC. The simulated phase distortion was co...
TL;DR: In this article, a short introduction on quantum thermodynamics is given and three new topics are discussed: work extraction from two-temperature set-ups, the presence of correlations can push the effective efficiency beyond the Carnot bound, and non-slow changes may be more optimal than slow ones.
Abstract: A short introduction on quantum thermodynamics is given and three new topics are discussed. (1) Maximal work extraction from a finite quantum system. The thermodynamic prediction fails and a new, general result is derived, the ‘ergotropy’. (2) In work extraction from two-temperature set-ups, the presence of correlations can push the effective efficiency beyond the Carnot bound. (3) In the presence of level crossing, non-slow changes may be more optimal than slow ones.
TL;DR: It is shown how to generally remove mixing of an encoded subspace with external states (termed leakage errors) using decoupling controls using ‘leakage elimination operations’ or ‘LEOs’.
Abstract: Quantum error prevention strategies will be required to produce a scalable quantum computing device and are of central importance in this regard. Progress in this area has been quite rapid in the past few years. In order to provide an overview of the achievements in this area, we discuss the three major classes of error prevention strategies, the abilities of these methods and the shortcomings. We then discuss the combinations of these strategies which have recently been proposed in the literature. Finally, we present recent results in reducing errors on encoded subspaces using decoupling controls. We show how to generally remove mixing of an encoded subspace with external states (termed leakage errors) using decoupling controls. Such controls are known as 'leakage elimination operations' or 'LEOs'.
TL;DR: In this paper, a gated-mode single-photon counters based on InGaAs/InP avalanche photodiodes were developed for use at 1.55mm wavelength.
Abstract: We have developed high speed gated-mode single-photon counters based on InGaAs/InP avalanche photodiodes for use at 1.55mm 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 � 10 � 15 WH z � 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 1.55mm 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.