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Dive into the research topics where Varun B. Verma is active.

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Featured researches published by Varun B. Verma.


Nature Photonics | 2013

Detecting single infrared photons with 93% system efficiency

Francesco Marsili; Varun B. Verma; Jeffrey A. Stern; S. Harrington; Adriana E. Lita; Thomas Gerrits; I. Vayshenker; Burm Baek; Matthew D. Shaw; Richard P. Mirin; Sae Woo Nam

Researchers develop a fiber-coupled single-photon-detection system using amorphous tungsten silicide superconducting nanowire single-photon detectors. The system detection efficiency is higher than 90% in the wavelength range between 1520 nm and 1610 nm. The device dark-count rate, timing jitter and reset time are 1 cps, 150 ps and 40 ns, respectively.


Physical Review Letters | 2015

Strong Loophole-Free Test of Local Realism

Lynden K. Shalm; Evan Meyer-Scott; Bradley G. Christensen; Peter Bierhorst; Michael A. Wayne; Martin J. Stevens; Thomas Gerrits; Scott C. Glancy; Deny R. Hamel; Michael S. Allman; Kevin J. Coakley; Shellee D. Dyer; Carson Hodge; Adriana E. Lita; Varun B. Verma; Camilla Lambrocco; Edward Tortorici; Alan L. Migdall; Yanbao Zhang; Daniel Kumor; William H. Farr; Francesco Marsili; Matthew D. Shaw; Jeffrey A. Stern; Carlos Abellan; Waldimar Amaya; Valerio Pruneri; Thomas Jennewein; Morgan W. Mitchell; Paul G. Kwiat

We performed an loophole-free test of Bells inequalities. The probability that local realism is compatible with our results is less than 5.9×10<sup>-9</sup>.


Applied Physics Letters | 2011

Superconducting a-WxSi1−x nanowire single-photon detector with saturated internal quantum efficiency from visible to 1850 nm

Burm Baek; Adriana E. Lita; Varun B. Verma; Sae Woo Nam

We have developed a single-photon detector based on superconducting amorphous tungsten–silicon alloy (a-WxSi1−x) nanowire. Our device made from a uniform a-WxSi1−x nanowire covers a practical detection area (16 μm×16 μm) and shows high sensitivity featuring a plateau of the internal quantum efficiencies, i.e., efficiencies of generating an electrical pulse per absorbed photon, over a broad wavelength and bias range. This material system for superconducting nanowire detector technology could overcome the limitations of the prevalent nanowire devices based on NbN and lead to more practical, ideal single-photon detectors having high efficiency, low noise, and high count rates.


Nature Materials | 2011

Epitaxial growth of three-dimensionally architectured optoelectronic devices

Erik C. Nelson; N. L. Dias; Kevin Bassett; Simon Dunham; Varun B. Verma; Masao Miyake; Pierre Wiltzius; John A. Rogers; J. J. Coleman; Xiuling Li; Paul V. Braun

Optoelectronic devices have long benefited from structuring in multiple dimensions on microscopic length scales. However, preserving crystal epitaxy, a general necessity for good optoelectronic properties, while imparting a complex three-dimensional structure remains a significant challenge. Three-dimensional (3D) photonic crystals are one class of materials where epitaxy of 3D structures would enable new functionalities. Many 3D photonic crystal devices have been proposed, including zero-threshold lasers, low-loss waveguides, high-efficiency light-emitting diodes (LEDs) and solar cells, but have generally not been realized because of material limitations. Exciting concepts in metamaterials, including negative refraction and cloaking, could be made practical using 3D structures that incorporate electrically pumped gain elements to balance the inherent optical loss of such devices. Here we demonstrate the 3D-template-directed epitaxy of group III-V materials, which enables formation of 3D structured optoelectronic devices. We illustrate the power of this technique by fabricating an electrically driven 3D photonic crystal LED.


Nature Photonics | 2015

Quantum storage of entangled telecom-wavelength photons in an erbium-doped optical fibre

Erhan Saglamyurek; Jeongwan Jin; Varun B. Verma; Matthew D. Shaw; Francesco Marsili; Sae Woo Nam; Daniel Oblak; Wolfgang Tittel

The authors report the storage and retrieval of entangled telecom-wavelength photons in an erbium-doped optical fibre.


Nature Photonics | 2014

Direct generation of three-photon polarization entanglement

Deny R. Hamel; Lynden K. Shalm; Hannes Hübel; Aaron J. Miller; Francesco Marsili; Varun B. Verma; Richard P. Mirin; Sae Woo Nam; Kevin J. Resch; Thomas Jennewein

A three-photon entangled Greenberger–Horne–Zeilinger state is directly produced by cascading two entangled down-conversion processes. Experimentally, 11.1 triplets per minute are detected on average. The three-photon entangled state is used for state tomography and as a test of local realism by violating the Mermin and Svetlichny inequalities.


Applied Physics Letters | 2015

A Near-Infrared 64-pixel Superconducting Nanowire Single Photon Detector Array with Integrated Multiplexed Readout

Michael S. Allman; Varun B. Verma; Martin J. Stevens; Thomas Gerrits; Robert D. Horansky; Adriana E. Lita; Francesco Marsili; Andrew D. Beyer; Matthew D. 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 number of readout lines to 16. The cryogenic, optical, and electronic packaging to read out the array, as well as characterization measurements are discussed.


Optics Express | 2015

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

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 report on MoSi SNSPDs which achieved high system detection efficiency (87.1 ± 0.5% at 1542 nm) at 0.7 K and we demonstrate that these detectors can also be operated with saturated internal efficiency at a temperature of 2.3 K in a Gifford-McMahon cryocooler. We measured a minimum system jitter of 76 ps, maximum count rate approaching 10 MHz, and polarization dependence as low as 3.3 ± 0.1%. The performance of MoSi SNSPDs at 2.3 K is similar to the performance of WSi SNSPDs at < 1 K. The higher operating temperature of MoSi SNSPDs makes these devices promising for widespread use due to the simpler and less expensive cryogenics required for their operation.


Nature Photonics | 2016

Quantum teleportation across a metropolitan fibre network

Raju Valivarthi; Marcel.li Grimau Puigibert; Qiang Zhou; Gabriel H. Aguilar; Varun B. Verma; Francesco Marsili; Matthew D. Shaw; Sae Woo Nam; Daniel Oblak; Wolfgang Tittel

The first field test of quantum teleportation is implemented across a metropolitan fibre network with independent quantum light sources. To establish a robust quantum teleportation system in the real world, several feedback mechanisms are developed.


Applied Physics Letters | 2014

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

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 dark count rates below 500 cps. Operation in a closed-cycle cryocooler at 2.5 K is possible with system detection efficiencies exceeding 20% for SNSPDs which have not been optimized for high detection efficiency. Jitter is observed to vary between 69 ps at 250 mK and 187 ps at 2.5 K using room temperature amplifiers.

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Sae Woo Nam

National Institute of Standards and Technology

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Richard P. Mirin

National Institute of Standards and Technology

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Francesco Marsili

Massachusetts Institute of Technology

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Matthew D. Shaw

California Institute of Technology

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Adriana E. Lita

National Institute of Standards and Technology

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Thomas Gerrits

National Institute of Standards and Technology

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Jeffrey A. Stern

California Institute of Technology

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Martin J. Stevens

National Institute of Standards and Technology

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Andrew D. Beyer

Jet Propulsion Laboratory

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Robert D. Horansky

National Institute of Standards and Technology

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