Indium arsenide quantum dots for single photons in the communications band

Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2013.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 75-78).This thesis presents work towards engineering and characterizing epitaxial Indium Arsenide (InAs) quantum dots as single photon sources in the optical communications C-Band (Conventional Band; 1535 nm-1565 nm wavelength). First, the underlying theory of semiconductor quantum dots and the necessary tools from quantum optics are reviewed. Next, a detailed description is given of the experimental system design, along with an overview of the design and implementation process of a cryogenic scanning laser confocal microscope. Then, the quantum dot growth process is presented along with the results of measurements on early quantum dot samples, which suggested that the initial growth process needed to be refined. We present efforts towards improving the growth process and measurements of quantum dot samples resulting from this new process.by Gregory R. Steinbrecher.M. Eng

High-fidelity quantum state evolution in imperfect photonic integrated circuits

We propose and analyze the design of a programmable photonic integrated circuit for high-fidelity quantum computation and simulation. We demonstrate that the reconfigurability of our design allows us to overcome two major impediments to quantum optics on a chip: it removes the need for a full fabrication cycle for each experiment and allows for compensation of fabrication errors using numerical optimization techniques. Under a pessimistic fabrication model for the silicon-on-insulator process, we demonstrate a dramatic fidelity improvement for the linear optics controlled-not and controlled-phase gates and, showing the scalability of this approach, the iterative phase estimation algorithm built from individually optimized gates. We also propose and simulate an experiment that the programmability of our system would enable: a statistically robust study of the evolution of entangled photons in disordered quantum walks. Overall, our results suggest that existing fabrication processes are sufficient to build a quantum photonic processor capable of high-fidelity operation.United States. Air Force Office of Scientific Research. Multidisciplinary University Research Initiative (Grant FA9550-14-1-0052)iQuISE FellowshipNational Science Foundation (U.S.). Graduate Research Fellowship (Grant 1122374)American Society for Engineering Education. National Defense Science and Engineering Graduate FellowshipAlfred P. Sloan Foundation (Sloan Research Fellowship

Large-scale quantum photonic circuits in silicon

Quantum information science offers inherently more powerful methods for communication, computation, and precision measurement that take advantage of quantum superposition and entanglement. In recent years, theoretical and experimental advances in quantum computing and simulation with photons have spurred great interest in developing large photonic entangled states that challenge today’s classical computers. As experiments have increased in complexity, there has been an increasing need to transition bulk optics experiments to integrated photonics platforms to control more spatial modes with higher fidelity and phase stability. The silicon-on-insulator (SOI) nanophotonics platform offers new possibilities for quantum optics, including the integration of bright, nonclassical light sources, based on the large third-order nonlinearity (χ(3)) of silicon, alongside quantum state manipulation circuits with thousands of optical elements, all on a single phase-stable chip. How large do these photonic systems need to be? Recent theoretical work on Boson Sampling suggests that even the problem of sampling from e30 identical photons, having passed through an interferometer of hundreds of modes, becomes challenging for classical computers. While experiments of this size are still challenging, the SOI platform has the required component density to enable low-loss and programmable interferometers for manipulating hundreds of spatial modes. Here, we discuss the SOI nanophotonics platform for quantum photonic circuits with hundreds-to-thousands of optical elements and the associated challenges. We compare SOI to competing technologies in terms of requirements for quantum optical systems. We review recent results on large-scale quantum state evolution circuits and strategies for realizing high-fidelity heralded gates with imperfect, practical systems. Next, we review recent results on silicon photonics-based photon-pair sources and device architectures, and we discuss a path towards large-scale source integration. Finally, we review monolithic integration strategies for single-photon detectors and their essential role in on-chip feed forward operations.United States. Air Force Office of Scientific Research (FA9550-14-1-0052)United States. Air Force Research Laboratory. RITA Program (FA8750-14-2-0120)American Society for Engineering Education. National Defense Science and Engineering Graduate FellowshipNational Science Foundation (U.S.). Graduate Research Fellowship Program (Grant 1122374)

Large-alphabet encoding for higher-rate quantum key distribution

The manipulation of high-dimensional degrees of freedom provides new opportunities for more efficient quantum information processing. It has recently been shown that high-dimensional encoded states can provide significant advantages over binary quantum states in applications of quantum computation and quantum communication. In particular, high-dimensional quantum key distribution enables higher secret-key generation rates under practical limitations of detectors or light sources, as well as greater error tolerance. Here, we demonstrate high-dimensional quantum key distribution capabilities both in the laboratory and over a deployed fiber, using photons encoded in a high-dimensional alphabet to increase the secure information yield per detected photon. By adjusting the alphabet size, it is possible to mitigate the effects of receiver bottlenecks and optimize the secret-key rates for different channel losses. This work presents a strategy for achieving higher secret-key rates in receiver-limited scenarios and marks an important step toward high-dimensional quantum communication in deployed fiber networks. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing AgreementU.S. Air Force [FA8721-05-C-0002, FA8702-15-D-0001]; Air Force Office of Scientific Research Multidisciplinary University Research Initiative [FA9550-14-1-0052]; Air Force Research Laboratory RITA [FA8750-14-2-0120, N00014-16-C-2069]Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Entanglement-based quantum communication secured by nonlocal dispersion cancellation

Quantum key distribution (QKD) enables participants to exchange secret information over long distances with unconditional security. However, the performance of today's QKD systems is subject to hardware limitations, such as those of available nonclassical-light sources and single-photon detectors. By encoding photons in high-dimensional states, the rate of generating secure information under these technical constraints can be maximized. Here, we demonstrate a complete time-energy entanglement-based QKD system with proven security against the broad class of arbitrary collective attacks. The security of the system is based on nonlocal dispersion cancellation between two time-energy entangled photons. This resource-efficient QKD system is implemented at telecommunications wavelength, is suitable for optical fiber and free-space links, and is compatible with wavelength-division multiplexing.United States. Army Research Office (Defense Advanced Research Projects Agency. Information in a Photon (InPho) Program (Grant W911NF-10-1-0416))National Science Foundation (U.S.). Integrative Graduate Education and Research Traineeship (Grant DGE-1069420

Programmable dispersion on a photonic integrated circuit for classical and quantum applications

We demonstrate a large-scale tunable-coupling ring resonator array, suitable for high-dimensional classical and quantum transforms, in a CMOS-compatible silicon photonics platform. The device consists of a waveguide coupled to 15 ring-based dispersive elements with programmable linewidths and resonance frequencies. The ability to control both quality factor and frequency of each ring provides an unprecedented 30 degrees of freedom in dispersion control on a single spatial channel. This programmable dispersion control system has a range of applications, including mode-locked lasers, quantum key distribution, and photon-pair generation. We also propose a novel application enabled by this circuit – high-speed quantum communications using temporal-mode-based quantum data locking – and discuss the utility of the system for performing the high-dimensional unitary optical transformations necessary for a quantum data locking demonstration

Programmable photonics for quantum and classical information processing

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019Cataloged from PDF version of thesis.Includes bibliographical references (pages 143-156).In this thesis, I explore the application of integrated photonic systems to quantum information processing as well as quantum and classical communications. The common thread throughout this work is the efficacy of variational numerical optimization in the design and optimization of photonic/bosonic systems. I present the programmable nanophotonic processor (PNP) platform that we developed, which is one way to realize an arbitrarily reconfigurable linear optics platform. I explore the prospects of realizing high fidelity quantum gates in this system, demonstrating through black box numerical optimization that we can compensate for a realistic model of fabrication error in the silicon photonics platform. Next, I discuss the design and construction of a next-generation PNP laboratory testbed, from the silicon photonics design up through the thermal and mechanical packaging, and the custom control and monitoring electronics. I discuss experiments using PNPs as a novel type of optical network switch, capable of both unicast and multicast operation, demonstrating its benefits in a small network testbed. Looking towards the future, I show that the integration of optical nonlinearities with PNPs would enable a quantum optical neural network (QONN) platform, demonstrating through simulation that these QONNs can be optimized to perform a variety of quantum and classical information processing tasks. I then expand the application of these systems from information processing to communications, showing that QONNs provide a natural platform to realize one-way quantum repeaters. Finally, I demonstrate the efficacy of the numerical techniques used in this thesis to a related system: cold atoms trapped in an optical lattice, the dynamics of which are similar to photons with interactions. We show that the optimization of the parameters of a simple one-dimensional model of this system can realize a universal gate set for quantum computing.by Gregory R. Steinbrecher.Ph. D.Ph.D. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Scienc