Linearly polarized single photons in the telecom ‘O’ band from a quantum dot in an elliptical bullseye resonatorBarbiero, A.; Shooter, G.; Müller, T.; Skiba-Szymanska, J.; Stevenson, R. M.; Goff, L. E.; Ritchie, D. A.; Shields, A. J.
doi: 10.1117/12.3001566pmid: N/A
Semiconductor quantum dots can generate single indistinguishable photons at telecom wavelengths for quantum networking applications. Integrating quantum dots into polarized microcavities is highly beneficial for advanced functionalities. In this work, we couple a quantum dot emitting in the telecom ‘O’ band to an elliptical bullseye resonator, demonstrating broadband polarization-selective enhancement and linearly polarized single-photon emission.
All-optical quantum memoryArnold, Nathan T.; Lualdi, Colin P.; Goggin, Michael E.; Kwiat, Paul G.
doi: 10.1117/12.3003228pmid: N/A
Quantum memories will be an essential part of many quantum information protocols, including distributed quantum computing, quantum sensing, and the synchronization of repeater nodes. Most efforts toward developing such a quantum memory have been focused on matter-based storage systems, which convert the energy and information from an optical state to an atomic state of matter to be retrieved later. These matter memories, while capable of achieving great storage times, have several limitations; namely, they are inherently narrow bandwidth, they typically do not operate at key telecommunications wavelengths, and often require costly overhead in the form of cryogenics. In this work, we have developed a quantum memory that operates in free space at room temperature, allowing us to avoid all the previously mentioned limitations, and achieve a record-high time-bandwidth product.
Quantum computing with oscillatory quantaPatel, Lalit A.
doi: 10.1117/12.3000438pmid: N/A
The linear superposition principle and the quantum entanglement phenomenon play crucial roles in the fields of quantum computing and information. Their current interpretations are not satisfactory for the need of quantum computing and information. To reduce the measurement-bias of the current interpretation of the quantum linear superposition principle, this paper presents an alternative interpretation: A physical quantity of a quantum object keeps oscillating between the allowed values of the physical quantity. Thus, a quantum system is inherently deterministic, but it appears to be probabilistic because of randomness in timings of measurements. Then, to show that the so-called quantum entangled objects need not interact or communicate with each other, the paper presents an alternative interpretation of the quantum entanglement phenomenon: Quantum objects appear to be entangled if and when each physical quantity of these objects undergoes synchronous oscillations. An experimental method is presented to validate this interpretation. Quantum entanglement due to synchronous oscillations can lead to more and better ways of quantum computers. The paper introduces Excel and Python quos package approaches to simplify and expedite designing and simulating quantum computing circuits.
Thin-film lithium niobate waveguides for quantum photonicsFejer, M. M.
doi: 10.1117/12.3010002pmid: N/A
Thin-film lithium niobate (TFLN) waveguides provide a flexible platform for classical and quantum photonics. Their tight optical confinement enables strong nonlinear coupling, dispersion engineering for broadband interactions, passive components such as filters and high-Q resonators, low-voltage high-speed electro-optic devices, and tight-radius bends for dense integration. The performance of TFLN devices will be compared with that obtained in conventional weakly guiding waveguides, with a focus on quantum frequency conversion, heralded single photon sources, and progress towards few-photon nonlinear interactions.
Resolving wave-particle duality could accelerate the mass production of quantum computersRoychoudhuri, Chandrasekhar; Prasad, Narasimha
doi: 10.1117/12.3001213pmid: N/A
Quantum computers, hypothesized in 1980s, use concepts of superposition and entanglement phenomena. Although theoretical propositions and associated search algorithms for accurate measurements are being generated, the development of practical quantum computers themselves are advancing very slowly requiring enormous time and investments. The underlying concepts of a quantum computer are not new to the optical domain. However, the crucial enabling concepts of Entanglement and Superposition Principle are remaining clouded under the unresolved postulates, Wave-Particle Duality (WPD), and Wave Packet Reduction (WPR), implicating incompleteness in the interpretations of the mathematical formalism behind Quantum Mechanics. The WPD debate started during late1600 between Newton and Huygens. Young’s resolution of WPD through his double-slit experiment in 1802 was effectively overturned by Einstein’s interpretation of photoelectric effect as due to “indivisible light quanta”. However, Einstein disowned his “light quanta” postulate shortly before his death in1955, even though it had earned him the Nobel Prize. We resolve WPD by synthesizing Newton’s and Maxwell’s concepts and assume atoms do emit quanta but propagate as time-finite exponential pulses. This assumption also resolves WPR for light-matter interaction with the assumption that Schrodinger’s ψ represents atom’s internal dipolar amplitude stimulations. This over-turns Born’s interpretation that ψ only represents the abstract mathematical probability amplitude, rather than the physical “internal amplitude stimulation” of the quantum entity. However, our concept of atomic pulse emission forces us to re-derive the expression for the N-slit grating-spectrometer response since the classical derivation uses CW light, which does not exist. This pulsespectrometric response function strengthens our postulate since the grating response to the exponential pulse appears to be the convolution of a Lorentzian spectrum with the classical CW response function of the grating. The Fourier Transform of an exponential function is Lorentzian and QM predicts spontaneous emission line width to be Lorentzian. Then, conceptually one can extend the grating-expression (with N=2) to get the double-slit pattern. This approach preserves the classical causality that each of the two slits, like the N-signals out of a grating, are physically real and jointly stimulate the quantum detector array at the far field to generate the “Local” cosine fringes. The detector array executes the square modulus operation on its imposed dipolar amplitude stimulation and absorbs the necessary energy to fill up their quantum cups. Hence the double-slit pattern must also be “Local”, just as the N-slit grating spectrum is generated locally at the exit spectral-plane of the spectrometer. This removes the need to believe that “single photons” mysteriously generate the double slit pattern.
A hybrid quantum-classical approach to warm-starting optimizationDehn, Vanessa; Wellens, Thomas
doi: 10.1117/12.3002220pmid: N/A
The Quantum Approximate Optimization Algorithm (QAOA) is a promising candidate for solving combinatorial optimization problems more efficiently than classical computers. Recent studies have shown that warm-starting the standard algorithm improves the performance. In this paper we compare the performance of standard QAOA with that of warm-start QAOA in the context of portfolio optimization and investigate the warm-start approach for different problem instances. In particular, we analyze the extent to which the improved performance of warm-start QAOA is due to quantum effects, and show that the results can be reproduced or even surpassed by a purely classical preprocessing of the original problem followed by standard QAOA.
Secure quantum random number generation with perovskite photonicsArgillander, Joakim; Alarcón, Alvaro; Bao, Chunxiong; Kuang, Chaoyang; Lima, Gustavo; Gao, Feng; Xavier, Guilherme B.
doi: 10.1117/12.2692061pmid: N/A
In the field of cryptography, it is crucial that the random numbers used in key generation are not only genuinely random but also private, meaning that no other party than the legitimate user must have information about the numbers generated. Quantum random number generators can offer both properties - fundamentally random output, as well as the ability to implement generators that can certify the amount of private randomness generated, in order to remove some side-channel attacks. In this study we introduce perovskite technology as a resilient platform for photonics, where the resilience is owed to perovskite’s ease of manufacturing. This has the potential to mitigate disruptions in the supply chain by enabling local and domestic manufacturing of photonic devices. We demonstrate the feasibility of the platform by implementing a measurement-device independent quantum random number generator based on perovskite LEDs.