Boris L. Glebov

Demonstrating highly symmetric single-mode, single-photon heralding efficiency in spontaneous parametric downconversion

We demonstrate a symmetric, single-spatial mode, single-photon heralding efficiency of 84% for a type-II spontaneous parametric downconversion process. High efficiency, single-spatial mode collection is key to enabling many quantum information processing and quantum metrology applications.

Photon-number-resolved detection of photon-subtracted thermal light.

We examine the photon statistics of photon-subtracted thermal light with photon-number-resolving detection. We show the photon-number distribution transforming from a Bose-Einstein distribution to a Poisson distribution as the number of subtracted photon increases.

Photon-number uncertainty in a superconducting transition edge sensor beyond resolved-photon-number determination

As part of an effort to extend fundamental single-photon measurements into the macroscopic regime, we explore how best to assign photon-number uncertainties to output waveforms of a superconducting transition edge sensor and how those assignments change over that extended dynamic range. Three methods are used. At the lowest photon numbers (up to 20 photons), the widths of histogram peaks of individual waveforms are used to determine the uncertainty. From 100 to 1000 photons, mean waveforms are used to create a photon-number scale. The photon-number uncertainty of the detector in this range is given by the excess of the total variance of the photon number obtained from individual waveforms on this scale beyond the shot noise due to the source. In the midrange (from 10 to 100 photons), including a range where the two other methods do not produce definitive results, we fit waveforms to several adjacent mean waveforms to estimate the photon-number uncertainty. A one-standard-deviation uncertainty in photon number of no more than ±1 is found for pulses of up to 100 photons.

Absolute calibration of a variable attenuator using few-photon pulses

We demonstrate the ability to calibrate a variable optical attenuator directly at the few-photon level using a superconducting Transition Edge Sensor (TES). Because of the inherent linearity of photon-number resolving detection, no external calibrations are required, even for the energy of the laser pulses, which ranged from means of 0.15 to 18 photons per pulse at the detector. To verify this method, calibrations were compared to an independent conventional calibration made at much higher photon fluxes using analog detectors. In all cases, the attenuations estimated by the two methods agree within their uncertainties.Our few-photon measurement determined attenuations using the Poisson-Influenced K-Means Algorithm (PIKA) to extract mean numbers of photons per pulse along with the uncertainties of these means. The robustness of the method is highlighted by the agreement of the two calibrations even in the presence of significant drifts in the optical power over the course of the experiment.Work of the United States Government. Not subject to copyright.

An improved method for photon-number discrimination for transition-edge sensors

Proposed discrimination of photon numbers is based on sum-squared error between an individual detector response curve and a calibration suite of response templates corresponding to a range of photon numbers. Templates for low numbers are obtained directly from data. Templates for higher photon numbers are extrapolated from fits describing incremental differences between successive low-number response templates.

Demonstrating high symmetric single-mode single-photon heralding efficiency in spontaneous parametric downconversion

We demonstrate a symmetric, single-spatial mode, single-photon heralding efficiency of 84% for a type-II spontaneous parametric downconversion process. High efficiency, single-spatial mode collection is key to enabling many quantum information processing and quantum metrology applications.