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Search Publications by: Varun Verma (Fed)

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Displaying 51 - 75 of 76

Quasiparticle recombination in hotspots in superconducting current-carrying nanowires

August 6, 2015
Author(s)
Alex Kozorezov, Colin Lambert, Francesco Marsili, Martin Stevens, Varun Verma, Jeffrey A. Stern, Rob Horansky, Shellee D. Dyer, Shannon Duff, David P. Pappas, Adriana Lita, Matthew D. Shaw, Richard Mirin, Sae Woo Nam
We describe a kinetic model of recombination of nonequilibrium quasiparticles generated by single photon absorption in superconducting current-carrying nanowires. The model is developed to interpret two-photon detection experiments in which a single photon

A near-infrared 64-pixel superconducting nanowire single photon detector array with integrated multiplexed readout

May 14, 2015
Author(s)
Michael S. Allman, Varun B. Verma, Martin J. Stevens, Thomas Gerrits, Robert D. Horansky, Adriana E. Lita, Francesco Marsili, A. Beyer, Matthew Shaw, D. Kumor, Richard P. Mirin, Sae Woo Nam
We demonstrate a 64-pixel free-space-coupled array of superconducting nanowire single photon detectors optimized for high detection efficiency in the near-infrared range. An integrated, readily scalable, multiplexed readout scheme is employed to reduce the

High-efficiency superconducting nanowire single-photon detectors fabricated from MoSi thin-films

April 10, 2015
Author(s)
Varun B. Verma, Boris Korzh, Felix Bussieres, Robert D. Horansky, Shellee D. Dyer, Adriana E. Lita, Igor Vayshenker, Francesco Marsili, Matthew D. Shaw, Hugo Zbinden, Richard P. Mirin, Sae Woo Nam
We demonstrate high-efficiency superconducting nanowire single-photon detectors (SNSPDs) fabricated from MoSi thin-films. We measure a maximum system detection efficiency (SDE) of 87 ± 0.5 % at 1542 nm at a temperature of 0.7 K, with a jitter of 76 ps

Photon-efficient high-dimensional quantum key distribution

February 4, 2015
Author(s)
Tian Zhong, Hongchao Zhou, Rob Horansky, Catherine Lee, Varun Verma, Adriana Lita, Alessandro Restelli, Joshua Bienfang, Richard Mirin, Thomas Gerrits, Sae Woo Nam, Francesco Marsili, Zhenshen Zhang, Ligong Wang, Dirk Englund, Gregory Wornell, Jeffrey Shapiro, Franco N. Wong
Quantum key distribution (QKD) is a secure communication technology whose security is guaranteed by the laws of physics. However, its widespread use has been hindered in part by low secure-key throughput due to the inherent loss and de-coherence of photons

Spectral Correlation Measurements at the Hong-Ou-Mandel Interference Dip

January 22, 2015
Author(s)
Thomas Gerrits, Francesco Marsili, Varun B. Verma, Lynden K. Shalm, Jeffrey A. Stern, Matthew Shaw, Richard P. Mirin, Sae Woo Nam
We present an efficient tool capable of measuring the spectral correlations between photons emerging from a Hong-Ou-Mandel interference configuration. We show that the Hong-Ou-Mandel interference visibility decreases as the photons’ frequency spread is

Pulse-to-pulse jitter measurement by photon correlation in high-ss lasers

January 20, 2015
Author(s)
Armand Lebreton, Abram Izo, Remy Braive, Nadia Belabas, Isabelle Sagnes, Francesco F. Marsili, Varun Verma, Sae Woo Nam, Thomas Gerrits, Isabelle Robert-Philip, Martin Stevens, Alexios Beveratos
The turn-on delay jitter in pulsed lasers in which a large fraction (β) of spontaneous emission is channeled into the lasing mode is measured by use of a photon correlation technique. This jitter is found to significantly increase with β, reaching values of

Materials Development for High Efficiency Superconducting Nanowire Single-Photon Detectors

January 1, 2015
Author(s)
Adriana E. Lita, Varun B. Verma, Robert D. Horansky, Jeffrey M. Shainline, Richard P. Mirin, Sae Woo Nam
Superconducting nanowire single-photon detectors (SNSPDs) based on ultra-thin films have become the preferred technology for applications that require high efficiency single-photon detectors with high speed, high timing resolution, and low dark count rates

Entanglement-based quantum communication secured by nonlocal dispersion cancellation

December 22, 2014
Author(s)
Catherine Lee, Zheshen Zhang, Greg Steinbrecher, Hongchao Zhou, Jacob Mower, Tian Zhong, Ligong Wang, Rob Horansky, Varun Verma, Richard Mirin, Francesco Marsili, Matthew Shaw, Sae Woo Nam, Gregory Wornell, Franco N. Wong, Jeffrey Shapiro, Dirk Englund
The principles of quantum mechanics enable new applications that address unsolved problems in communications, computation, and precision measurement. Quantum key distribution (QKD) enables participants to amplify secure information over long distances with

High-efficiency WSi superconducting nanowire single-photon detectors operating at 2.5 K

September 24, 2014
Author(s)
Varun B. Verma, Boris Korzh, Felix Bussieres, Robert D. Horansky, Adriana E. Lita, Francesco Marsili, Hugo Zbinden, Richard P. Mirin, Sae Woo Nam
We demonstrate that superconducting nanowire single photon detectors (SNSPDs) fabricated from amorphous WSi may be operated with > 75 % system detection efficiency at a temperature approaching seventy percent of the superconducting transition temperature

Superconducting nanowire single photon detectors fabricated from an amorphous Mo0.75Ge0.25 thin-film

July 15, 2014
Author(s)
Varun B. Verma, Adriana E. Lita, Michael R. Vissers, Francesco Marsili, David P. Pappas, Richard P. Mirin, Sae Woo Nam
We present the characteristics of superconducting nanowire single photon detectors (SNSPDs) fabricated from amorphous Mo0.75Ge0.25 thin -films. Fabricated devices show a saturation of the internal detection efficiency at temperatures below 1 K, with system

Photon-Efficient High-Dimensional Quantum Key Distribution

June 12, 2014
Author(s)
Tian Zhong, Hongchao Zhou, Ligong Wang, Gregory Wornell, Zheshen Zhang, Jeffrey Shapiro, Franco N. Wong, Rob Horansky, Varun Verma, Adriana Lita, Richard Mirin, Thomas Gerrits, Sae Woo Nam, Alessandro Restelli, Joshua Bienfang, Francesco Marsili, Matthew Shaw
We demonstrate two high-dimensional QKD protocols - secure against collective Gaussian attacks - yielding up to 8.6 secure bits per photon and 6.7 Mb/s throughput, with 6.9 bits per photon after transmission through 20 km of fiber.

Gain and Loss in active waveguides based on lithographically defined quantum dots

June 1, 2014
Author(s)
Kevin L. Silverman, Luis Miaja Avila, Varun B. Verma, Richard P. Mirin, James J. Coleman
We report on the optical gain and loss of waveguides containing lithographically defined quantum dots. Lasing action has previously been demonstrated in a nominally identical structure. Measurements are made by monitoring the transmission of a resonant

Direct generation of three-photon polarization entanglement

April 28, 2014
Author(s)
Deny Hamel, Krister Shalm, Hannes Hubel, Aaron J. Miller, Francesco F. Marsili, Varun Verma, Richard Mirin, Sae Woo Nam, Kevin Resch, Thomas Jennewein
Non-classical states of light are of fundamental importance for emerging quantum technologies. All optics experiments producing multi-qubit entangled states have until now relied on outcome post-selection, a procedure where only the measurement results

Ultrafast optical properties of lithographically defined quantum dot amplifiers

February 10, 2014
Author(s)
Luis Miaja Avila, Varun B. Verma, James J. Coleman, Richard P. Mirin, Kevin L. Silverman
We measure the ultrafast optical response of lithographically defined quantum dot amplifiers at 40 K. Recovery of the gain mostly occurs in less than 1 picosecond, with some longer-term transients attributable to carrier heating. Recovery of the absorption

A four-pixel single-photon pulse-position array fabricated from WSi superconducting nanowire single- photon detectors

February 3, 2014
Author(s)
Varun B. Verma, Robert D. Horansky, Francesco Marsili, Jeffrey Stern, Matthew Shaw, Adriana E. Lita, Richard P. Mirin, Sae Woo Nam
We demonstrate a scalable readout scheme for an infrared single-photon pulse-position camera consisting of WSi superconducting nanowire single-photon detectors. For an N × N array, only 2 × N wires are required to obtain the position of a detection event

Quantum teleportation from a telecom-wavelength photon to a solid-state quantum memory

January 28, 2014
Author(s)
Felix Bussieres, Christoph Clausen, Alexey Tiranov, Boris Korzh, Varun Verma, Sae Woo Nam, Francesco Marsili, Alban Ferrier, Harald Hermann, Christine Silberhorn, Wolfgang Sohler, Mikael Afzelius, Nicolas Gisin
In quantum teleportation [1], the state of a single quantum system is disembodied into classical information and purely quantum correlations, to be later reconstructed onto a second system that has never directly interacted with the first one. This

Detecting Single Infrared Photons with 93 % System Efficiency

February 25, 2013
Author(s)
Francesco F. Marsili, Varun B. Verma, Jeffrey A. Stern, Sean D. Harrington, Adriana E. Lita, Thomas Gerrits, Igor Vayshenker, Burm Baek, Matthew D. Shaw, Richard P. Mirin, Sae Woo Nam
Single-photon detectors (SPDs) are nonlinear transducers that respond to the absorption of one or more photons with an electrical signal1. SPDs at near infrared wavelengths with high system detection efficiency (> 90%), low dark count rate (

Joint Spectral Measurements at the Hong-Ou-Mandel Interference Dip

January 29, 2013
Author(s)
Thomas Gerrits, Francesco F. Marsili, Varun B. Verma, Adriana E. Lita, Antia A. Lamas-Linares, Jeffrey A. Stern, Matthew Shaw, William Farr, Richard P. Mirin, Sae Woo Nam
We employed a 2 channel single-photon detection system with high detection efficiency and low jitter to characterize the joint spectral distribution (JSD) of the correlated photons emerging from a Hong-Ou-Mandel interference arrangement. We show the JSDs

Higher-order photon correlations in pulsed photonic crystal nanolasers

December 16, 2011
Author(s)
D. Elvira, X. Hachair, Varun Verma, R. Braive, G. Beaudoin, I. Robert-Philip, I. Sagnes, Burm Baek, Sae Woo Nam, E Dauler, I. Abram, Martin Stevens, A. Beveratos
We report on the higher-order photon correlations of a high-Β nanolaser under pulsed excitation at room temperature. Using a multiplexed four-element superconducting single-photon detector we measured g (n)(0) with n = 2,3,4. All orders of correlation

Time-resolved photoluminescence of lithographically defined quantum dots fabricated by electron beam lithography and wet chemical etching

June 15, 2011
Author(s)
Varun B. Verma, Martin J. Stevens, Kevin L. Silverman, Neville Dias, Akash Garg, James J. Coleman, Richard P. Mirin
We measure the time-resolved photoluminescence characteristics of a novel type of lithographically patterned quantum dot fabricated by electron beam lithography, wet chemical etching, and overgrowth of the barrier layers by metalorganic chemical vapor