Customer Publications

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Title: Quantum receiver enhanced by adaptive learning

Authors: Chaohan Cui¹, William Horrocks¹, Shuhong Hao², Saikat Guha^1,3, Nasser Peyghambarian^1,2, Quntao Zhuang^1,3,4, and Zheshen Zhang^1,2,3,5

¹James C. Wyant College of Optical Sciences, University of Arizona, Tucson, AZ
85721, USA. ²Department of Materials Science and Engineering, University of
Arizona, Tucson, AZ 85721, USA. ³Department of Electrical and Computer
Engineering, University of Arizona, Tucson, AZ 85721, USA. ⁴Department of
Electrical and Computer Engineering, University of Southern California, Los
Angeles, CA 90089, USA. ⁵Department of Electrical Engineering and Computer
Science, University of Michigan, Ann Arbor, MI 48109, USA.

Abstract

Quantum receivers aim to effectively navigate the vast quantum-state space to endow quantum information processing capabilities unmatched by classical receivers. To date, only a handful of quantum receivers have been constructed to tackle the problem of discriminating coherent states. Quantum receivers designed by analytical approaches, however, are incapable of effectively adapting to diverse environmental conditions, resulting in their quickly diminishing performance as the operational complexities increase. Here, we present a general architecture, dubbed the quantum receiver enhanced by adaptive learning, to adapt quantum receiver structures to diverse operational conditions. The adaptively learned quantum receiver is experimentally implemented in a hardware platform with record-high efficiency. Combining the architecture and the experimental advances, the error rate is reduced up to 40% over the standard quantum limit in two coherent-state encoding schemes.

Full Paper

Title: Functional Time Domain Diffuse Correlation Spectroscopy

Authors: Nisan Ozana¹, Niyom Lue², Marco Renna¹, Mitchell B Robinson^1,3, Alyssa Martin¹, Alexander I Zavriyev¹, Bryce Carr¹, Dibbyan Mazumder¹, Megan H Blackwell², Maria A Franceschini¹, and Stefan A Carp¹

¹Department of Radiology, Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States.²Massachusetts Institute of Technology Lincoln Laboratory, Lexington, MA, United States.³Massachusetts Institute of Technology, Health Sciences and Technology Program, Cambridge, MA, United States.

Abstract

Time-domain diffuse correlation spectroscopy (TD-DCS) offers a novel approach to high-spatial resolution functional brain imaging based on the direct quantification of cerebral blood flow (CBF) changes in response to neural activity. However, the signal-to-noise ratio (SNR) offered by previous TD-DCS instruments remains a challenge to achieving the high temporal resolution needed to resolve perfusion changes during functional measurements. Here we present a next-generation optimized functional TD-DCS system that combines a custom 1,064 nm pulse-shaped, quasi transform-limited, amplified laser source with a high-resolution time-tagging system and superconducting nanowire single-photon detectors (SNSPDs). System characterization and optimization was conducted on homogenous and two-layer intralipid phantoms before performing functional CBF measurements in six human subjects. By acquiring CBF signals at over 5 Hz for a late gate start time of the temporal point spread function (TPSF) at 15 mm source-detector separation, we demonstrate for the first time the measurement of blood flow responses to breath-holding and functional tasks using TD-DCS.

Full Paper

Title: Superconducting nanowire single-photon sensing of cerebral blood flow

Authors: Nisan Ozana¹, Alexander I. Zavriyev¹, Dibbyan Mazumder¹, Mitchell Robinson^1,2, Kutlu Kaya¹, Megan Blackwell³, Stefan A. Carp¹, and Maria Angela Franceschini¹

¹Massachusetts General Hospital, Harvard Medical School, Optics at Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Boston, Massachusetts, USA. ²Massachusetts Institute of Technology, Health Sciences and Technology Program, Cambridge, Massachusetts, USA. ³Massachusetts Institute of Technology Lincoln Laboratory, Lexington, Massachusetts, USA.

Abstract

Significance: The ability of diffuse correlation spectroscopy (DCS) to measure cerebral blood flow (CBF) in humans is hindered by the low signal-to-noise ratio (SNR) of the method. This limits the high acquisition rates needed to resolve dynamic flow changes and to optimally filter out large pulsatile oscillations and prevents the use of large source-detector separations (≥3 cm), which are needed to achieve adequate brain sensitivity in most adult subjects.
Aim: To substantially improve SNR, we have built a DCS device that operates at 1064 nm and uses superconducting nanowire single-photon detectors (SNSPD).
Approach: We compared the performances of the SNSPD-DCS in humans with respect to typical DCS system operating at 850 nm and using silicon single-photon avalanche diode detectors.
Results: At a 25-mm separation, we detected 13 ± 6 times more photons and achieved an SNR gain of 16 ± 8 on the forehead of 11 subjects using the SNSPD-DCS as compared to typical DCS. At this separation, the SNSPD-DCS is able to detect a clean pulsatile flow signal at 20 Hz in all subjects. With the SNSPD-DCS, we also performed measurements at 35 mm, showing a lower scalp sensitivity of 31 ± 6% with respect to the 48 ± 8% scalp sensitivity at 25 mm for both the 850 and 1064 nm systems. Furthermore, we demonstrated blood flow responses to breath holding and hyperventilation tasks.
Conclusions: While current commercial SNSPDs are expensive, bulky, and loud, they may allow for more robust measures of non-invasive cerebral perfusion in an intensive care setting.

Full Paper

Title: Noninvasive Optical Monitoring of Cerebral Blood Flow and EEG Spectral Responses after Severe Traumatic Brain Injury: A Case Report

Authors: Chien-Sing Poon¹, Benjamin Rinehart¹, Dharminder S. Langri¹, Timothy M. Rambo², Aaron J. Miller², Brandon Foreman³, and Ulas Sunar¹

¹Department of Biomedical Engineering, Wright State University, Dayton, OH 45435, USA. ²Quantum Opus, LLC, Novi, MI 48375, USA. ³Department of Neurology & Rehabilitation Medicine, University of Cincinnati, Cincinnati, OH 45267, USA.

Abstract

Survivors of severe brain injury may require care in a neurointensive care unit (neuro-ICU),
where the brain is vulnerable to secondary brain injury. Thus, there is a need for noninvasive, bedside, continuous cerebral blood flow monitoring approaches in the neuro-ICU. Our goal is to address this need through combined measurements of EEG and functional optical spectroscopy (EEG-Optical) instrumentation and analysis to provide a complementary fusion of data about brain activity and function. We utilized the diffuse correlation spectroscopy method for assessing cerebral blood flow at the neuro-ICU in a patient with traumatic brain injury. The present case demonstrates the feasibility of continuous recording of noninvasive cerebral blood flow transients that correlated well with the gold-standard invasive measurements and with the frequency content changes in the EEG data.

Full Paper

Title: Quantum computational advantage using photons

Authors: Han-Sen Zhong^1,2, Hui Wang^1,2, Yu-Hao Deng^1,2, Ming-Cheng Chen^1,2, Li-Chao Peng^1,2, Yi-Han Luo^1,2, Jian Qin^1,2, Dian Wu^1,2, Xing Ding^1,2, Yi Hu^1,2, Peng Hu³, Xiao-Yan Yang³, Wei-Jun Zhang³, Hao Li³, Yuxuan Li⁴, Xiao Jiang^1,2, Lin Gan⁴, Guangwen Yang⁴, Lixing You³, Zhen Wang³, Li Li^1,2, Nai-Le Liu^1,2, Chao-Yang Lu^1,2, Jian-Wei Pan^1,2

¹Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China. ²CAS Centre for Excellence and Synergetic Innovation Centre in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China. ³State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China. ⁴Department of Computer Science and Technology and Beijing National Research Center for Information Science and Technology, Tsinghua University, Beijing 100084, China.

Abstract

Quantum computers promise to perform certain tasks that are believed to be intractable to classical computers. Boson sampling is such a task and is considered a strong candidate to demonstrate the quantum computational advantage. We performed Gaussian boson sampling by sending 50 indistinguishable single-mode squeezed states into a 100-mode ultralow-loss interferometer with full connectivity and random matrix—the whole optical setup is phase-locked—and sampling the output using 100 high-efficiency single-photon detectors. The obtained samples were validated against plausible hypotheses exploiting thermal states, distinguishable photons, and uniform distribution. The photonic quantum computer, Jiuzhang, generates up to 76 output photon clicks, which yields an output state-space dimension of 10³⁰ and a sampling rate that is faster than using the state-of-the-art simulation strategy and supercomputers by a factor of ~10¹⁴.

Full Paper

Title: Detector channel combining results from a high photon efficiency optical communications link test bed

Authors: Jennifer N. Downey, Brian E. Vyhnalek, Sarah A. Tedder, and Nicholas C. Lantz

NASA Glenn Research Center 21000 Brookpark Road, Cleveland, Ohio 44135, USA.

Abstract

The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) is developing a low cost, scalable, photon-counting receiver prototype for space-to-ground optical communications links. The receiver is being tested in a test bed that emulates photon-starved space-to-ground optical communication links. The receiver uses an array of single-pixel fiber coupled superconducting nanowire single-photon detectors. The receiver is designed to receive the high photon efficiency serially concatenated pulse position modulation (SCPPM) waveform specified in the Consultative Committee for Space Data Systems (CCSDS) Optical Communications Coding and Synchronization Blue Book Standard. The optical receiver consists of an array of single-pixel superconducting nanowire detectors, analog phase shifters for channel alignment, digitizers for each detector channel, and digital processing of the received signal. An overview of the test bed and arrayed receiver system is given. Simulation and system characterization results are presented. The data rate increase of using a four-channel arrayed detector system over using one single pixel nanowire detector is characterized. Results indicate that a single-pixel detector is capable of receiving data at a rate of 40 Mbps and a four-channel arrayed detector system is capable of receiving data at a rate of 130 Mbps.

Full Paper

Title: Generation of broadband correlated photon-pairs in short thin-film lithium-niobate waveguides

Authors: Bradley S. Elkus¹, Kamal Abdelsalam², Ashutosh Rao^2,3, Vesselin Velev^1,4, Sasan Fathpour², Prem Kumar¹, Gregory S. Kanter¹

¹Department of Electrical and Computer Engineering, Center for Photonic Communication and Computing, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3118, USA. ²CREOL, The College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816, USA. ³Currently with the Microsystems and Nanotechnology Division, Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA, and the University of Maryland, College Park, Maryland 20742, USA. ⁴Currently with Elenion Technologies, 171 Madison Ave #1100, New York, NY 10016, USA.

Abstract

An efficient source of quantum-correlated photon-pairs that is integrable with existing silicon-electronics fabrication techniques is desirable for use in quantum photonic integrated circuits. Here we demonstrate signal-idler photon pairs with high coincidence-to-accidental count ratios of over 103 on a coarse wavelength-division-multiplexing grid that spans 140 nm by using a 300-µm-long poled region in a thin-film periodically-poled lithium-niobate ridge waveguide bonded to silicon. The pairs are generated via spontaneous parametric downconversion pumped by a continuous-wave tunable laser source. The small mode area of the waveguide allows for efficient interaction in a short length of the waveguide and, as a result, permits photon-pair generation over a broad range of signal-idler wavelengths.

Full Paper

Title: Real Time Photon-Counting Receiver for High Photon Efficiency Optical Communications

Authors: Jennifer N. Downey, Brian E. Vyhnalek, Sarah A. Tedder, and Nicholas C. Lantz

NASA Glenn Research Center 21000 Brookpark Road, Cleveland, Ohio 44135, USA.

Abstract

We present a scalable design for a photon-counting ground receiver based on superconducting nanowire single photon detectors (SNSPDs) and field programmable gate array (FPGA) real-time processing for applications to space-to-ground photon starved links, such as the Orion EM-2 Optical Communication Demonstration (O2O), and future deep space or low transmitter power missions. The receiver is designed to receive a serially concatenated pulse position modulation (SCPPM) waveform, which follows the Consultative Committee for Space Data Systems (CCSDS) Optical Communications Coding and Synchronization Red Book standard. The receiver design uses multiple individually fiber coupled, 80% detection efficiency commercial SNSPDs in parallel to scale to a required data rate, and is capable of achieving data rates up to 528 Mbps. For efficient fiber coupling from the telescope to the array of parallel detectors that can be scaled both to telescope aperture size and the number of detectors, we use either a single mode fiber (SMF) photonic lantern or a few-mode fiber (FMF) photonic lantern. In this paper we give an overview of the receiver system design, the characteristics of the photonic lanterns, the performance of the SNSPDs, and system level tests. We show that 40 Mbps can be received using a single SNSPD, and discuss aspects for scaling to higher data rates.

Full Paper

Title: Decay-Associated Fourier Spectroscopy: Visible to Shortwave Infrared Time-Resolved Photoluminescence Spectra

Authors: Timothy L. Atallah, Anthony V. Sica, Ashley J. Shin, Hannah C. Friedman, Justin R. Caram

Department of Chemistry and Biochemistry, University of California, Los Angeles, 607 Charles E. Young Drive, Los Angeles, California 90095-1569, USA

Abstract

We describe and implement an interferometric approach to decay associated photoluminescence spectroscopy, which we term decay associated Fourier spectroscopy (DAFS). In DAFS, the emitted photon stream from a substrate passes through a variable path length Mach-Zehnder interferometer prior to detection and timing. The interferometer encodes spectral information in the intensity measured at each detector enabling simultaneous spectral and temporal resolution. We detail several advantages of DAFS, including wavelength-range insensitivity, drift-noise cancellation, and optical mode retention. DAFS allows us to direct the photon stream into an optical fiber, enabling the implementation of superconducting nanowire single photon detectors for energy-resolved spectroscopy in the shortwave infrared spectral window (λ=1-2 μm). We demonstrate the broad applicability of DAFS, in both the visible and shortwave infrared, using two Förster resonance energy transfer pairs: a pair operating with conventional visible wavelengths and a pair showing concurrent acquisition in the visible and the shortwave infrared regime.

Full Paper

Title: Few-mode fiber coupled superconducting nanowire single-photon detectors for photon efficient optical communications

Authors: Brian E. Vyhnalek, Sarah A. Tedder, Evan J. Katz, and Jennifer M. Nappier

National Aeronautics and Space Administration, Glenn Research Center, Cleveland, OH, USA.

Abstract

The NASA Glenn Research Center’s development of a high-photon efficiency real-time optical communications ground receiver has added superconducting nanowire single-photon detectors (SNSPDs) coupled with few-mode fibers (FMF). High data rate space-to-ground optical communication links require enhanced ground receiver sensitivity to reduce spacecraft transmitter constraints, and therefore require highly efficient coupling from fiber to detector. In the presence of atmospheric turbulence the received optical wavefront can be severely distorted introducing higher-order spatial mode components to the received signal. To reduce mode filtering and mismatch loss and the resulting degradations to detector coupling efficiency, we explore the use of few-mode fiber coupling to commercial single-pixel SNSPDs. Graded index 20-µm few-mode fibers allow the commercial single pixel SNSPD’s active area to couple with equal efficiency as single mode fibers. Here we determine detector characteristics such as count rate, detection efficiency, dark counts, and jitter, as well as detection efficiencies for higher-order fiber spatial modes. Additionally, we assess the laboratory performance of the detectors in an optical system which emulates future deep space optical communications links.

Full Paper

Title: Experimental rejection of observer-independence in the quantum world

Authors: Massimiliano Proietti¹, Alexander Pickston¹, Francesco Graffitti¹, Peter Barrow¹, Dmytro Kundys¹, Cyril Branciard², Martin Ringbauer^1,3, and Alessandro Fedrizzi¹

¹Scottish Universities Physics Alliance (SUPA), Institute of Photonics and Quantum Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK. ²Université Grenoble Alpes, CNRS, Grenoble INP, Institut Néel, 38000 Grenoble, France. ³Institut für Experimentalphysik, Universität Innsbruck, 6020 Innsbruck, Austria.

Abstract

The scientific method relies on facts, established through repeated measurements and agreed upon universally, independently of who observed them. In quantum mechanics, the objectivity of observations is not so clear, most dramatically exposed in Eugene Wigner’s eponymous thought experiment where two observers can experience fundamentally different realities. While observer-independence has long remained inaccessible to empirical investigation, recent no-go theorems construct an extended Wigner’s friend scenario with four entangled observers that allows us to put it to the test. In a state-of-the-art 6-photon experiment, we here realise this extended Wigner’s friend scenario, experimentally violating the associated Bell-type inequality by 5 standard deviations. This result lends considerable strength to interpretations of quantum theory already set in an observer-dependent framework and demands for revision of those which are not.

Full Paper

Title: Generation of multiphoton entangled quantum states by means of integrated frequency combs

Authors: Christian Reimer, Michael Kues, Piotr Roztocki, Benjamin Wetzel, Fabio Grazioso, Brent E. Little, Sai T. Chu, Tudor Johnston, Yaron Bromberg, Lucia Caspani, David J. Moss, Roberto Morandotti

Institut National de la Recherche Scientifique–Énergie Matériaux Télécommunications 
(Website)

Abstract

Complex optical photon states with entanglement shared among several modes are critical to improving our fundamental understanding of quantum mechanics and have applications for quantum information processing, imaging, and microscopy. We demonstrate that optical integrated Kerr frequency combs can be used to generate several bi- and multiphoton entangled qubits, with direct applications for quantum communication and computation. Our method is compatible with contemporary fiber and quantum memory infrastructures and with chip-scale semiconductor technology, enabling compact, low-cost, and scalable implementations. The exploitation of integrated Kerr frequency combs, with their ability to generate multiple, customizable, and complex quantum states, can provide a scalable, practical, and compact platform for quantum technologies.

Full Paper

Title: Certifying the Presence of a Photonic Qubit by Splitting It in Two

Authors: Evan Meyer-Scott, Daniel McCloskey, Klaudia Gołos, Jeff Z. Salvail, Kent A. G. Fisher, Deny R. Hamel, Adán Cabello, Kevin J. Resch, and Thomas Jennewein

Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo 
(Website)

Abstract

We present an implementation of photonic qubit precertification that performs the delicate task of detecting the presence of a flying photon without destroying its qubit state, allowing loss-sensitive quantum cryptography and tests of nonlocality even over long distance. By splitting an incoming single photon in two via parametric down-conversion, we herald the photon’s arrival from an independent photon source while preserving its quantum information with up to (92.3±0.6)% fidelity. With reduced detector dark counts, precertification will be immediately useful in quantum communication.

Full Paper

Title: On-chip generation of photon-triplet states

Authors: Stephan Krapick, Benjamin Brecht, Harald Herrmann, Viktor Quiring, and Christine Silberhorn

Applied Physics, University of Paderborn 
(Website)

Abstract

Efficient sources of many-partite non-classical states are key for the advancement of quantum technologies and for the fundamental testing of quantum mechanics. We demonstrate the generation of time-correlated photon triplets at telecom wavelengths via pulsed cascaded parametric down-conversion in a monolithically integrated source. By detecting the generated states with success probabilities of (6.25 ± 1.09) × 10⁻¹¹ per pump pulse at injected powers as low as 10 μW, we benchmark the efficiency of the complete system and deduce its high potential for scalability. Our source is unprecedentedly long-term stable, it overcomes interface losses intrinsically due to its monolithic architecture, and the photon-triplet states dominate uncorrelated noise significantly. These results mark crucial progress towards the proliferation of robust, scalable, synchronized and miniaturized quantum technology.

Full Paper

Title: Observation of genuine three-photon interference

Authors: Sascha Agne, Thomas Kauten, Jeongwan Jin, Evan Meyer-Scott, Jeff Z. Salvail, Deny R. Hamel, Kevin J. Resch, Gregor Weihs, Thomas Jennewein

Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo 
(Website)

Abstract

Multiparticle quantum interference is critical for our understanding and exploitation of quantum information, and for fundamental tests of quantum mechanics. A remarkable example of multi-partite correlations is exhibited by the Greenberger-Horne-Zeilinger (GHZ) state. In a GHZ state, three particles are correlated while no pairwise correlation is found. The manifestation of these strong correlations in an interferometric setting has been studied theoretically since 1990 but no three-photon GHZ interferometer has been realized experimentally. Here we demonstrate three-photon interference that does not originate from two-photon or single photon interference. We observe phase-dependent variation of three-photon coincidences with 90.5 ± 5.0 % visibility in a generalized Franson interferometer using energy-time entangled photon triplets. The demonstration of these strong correlations in an interferometric setting provides new avenues for multiphoton interferometry, fundamental tests of quantum mechanics and quantum information applications in higher dimensions.

Full Paper

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