This PDF file contains the front matter associated with SPIE Proceedings Volume 11726, including the Title Page, Copyright information and Table of Contents

The Illinois Express Quantum Network (IEQNET) is a program to realize metro-scale quantum networking over deployed optical fiber using currently available technology. IEQNET consists of multiple sites that are geographically dispersed in the Chicago metropolitan area. Each site has one or more quantum nodes (Qnodes) representing the communication parties in a quantum network. Q-nodes generate or measure quantum signals such as entangled photons and communicate the results via standard, classical, means. The entangled photons in IEQNET nodes are generated at multiple wavelengths, and are selectively distributed to the desired users via optical switches. Here we describe the network architecture of IEQNET, including the Internet-inspired layered hierarchy that leverages software-defined-networking (SDN) technology to perform traditional wavelength routing and assignment between the Q-nodes. Specifically, SDN decouples the control and data planes, with the control plane being entirely classical. Issues associated with synchronization, calibration, network monitoring, and scheduling will be discussed. An important goal of IEQNET is demonstrating the extent to which the control plane can coexist with the data plane using the same fiber lines. This goal is furthered by the use of tunable narrow-band optical filtering at the receivers and, at least in some cases, a wide wavelength separation between the quantum and classical channels. We envision IEQNET to aid in developing robust and practical quantum networks by demonstrating metro-scale quantum communication tasks such as entanglement distribution and quantum-state teleportation.

Mathematical analysis is presented related to novel quantum entangled states useful for interferometry. For interferometry applications, the approach based on entanglement presented here, even in the presence of loss offers a quadratic reduction in the number of photons required while maximizing phase sensitivity and visibility. Reducing the number of photons decreases the effects of certain mechanisms that degrade results. The new interferometer is an improvement on a previous interferometer based on linear combination of M&N states (LCMNS). LCMNS have been shown to be much more robust in the presence of environmental effects than plain M&N states or N00N states. Adaptive optics techniques are used to adjust the coefficients of the LCMNS. Closed form expressions for the minimum phase error, visibility, and coefficients are derived. Environmental effects are included using open systems theory. Numerical results are provided.

In the quantum logic of the DNA molecule, electrons are held and conducted coherently as spinless Cooper pairs and are shielded from electromagnetic energy by a Faraday cage effect of the double lipid bilayer of the nuclear membrane. The magnetic vector potential generated by cellular depolarization can synchronize logical activity in portions of the DNA molecule by affecting spin directions of appropriately oriented spinless electrons via the Aharonov-Bohm effect, but is not blocked by that Faraday cage effect. Within the logically and thermodynamically reversible chiral enantiomeric symmetry of the deoxyribose moieties the decoherent transition of Cooper pair to Dirac pair in a p-orbital of the C2-C3 covalent bond effects chiral selection between the C2-endo and C3-endo conformations. Such a spin-1/2 chiral collective movement of particles can be considered as a quasiparticle excitation that is its own antiparticle (C2-endo vs. C3-endo), meeting the definition of a Majorana fermion.

Quantum sensing is an important application of Quantum Information techniques. In this work, we present a mathematical model for a single Qutrit in Λ (Lambda) configuration and its quantum Fisher information.

Given a background space and a quantum tensor network, we de- scribe how to construct a new topological space, that welds the network and the background space together. This construction embodies the principle that quantum entanglement and topological connectivity are intimately related.

Many quantum computing algorithms are being developed with the advent of quantum computers. Solving linear systems is one of the most fundamental problems in almost all of science and engineering. HHL algorithm, a monumental quantum algorithm for solving linear systems on the gate model quantum computers, was invented and several advanced variations have been developed. However, HHL-based algorithms have a lot of limitations in spite of their importance. We address solving linear systems on a D-Wave quantum annealing device. To formulate a quadratic unconstrained binary optimization (QUBO) model for a linear system solving problem, we make use of a linear least-square problem with binary representation of the solution. We validate this QUBO model on the D-Wave system and discuss the results.

The electromagnetic spectrum is limited. As demand increases, our capabilities will be dictated by the sensitivity and agility of RF transmitters, receivers, and networks. For this reason, quantum RF sensors and networks are the key to controlling the spectrum in the tomorrow's competitive landscape. Here, we present a Rydberg-atom based quantum spectrum analyzer that operates continuously from zero to 20 GHz, with sensitivity and instantaneous bandwidth that rivals high-end conventional spectrum analyzers. The spectrum analyzer uses room-temperature Rydberg atoms coupled to an RF waveguide, and input signals are amplified using an off-resonant atomic heterodyne technique. We measure weak ambient signals inside the laboratory including AM/FM radio, Wi-Fi, and Bluetooth. The quantum spectrum analyzer is characterized by unique capabilities that will allow it, in the near future, to surpass foundational limitations of traditional RF receivers and analyzers.

Quantum technologies containing key GaN laser components will enable a new generation of precision sensors, optical atomic clocks and secure communication systems for many applications such as next generation navigation, gravity mapping and timing since the AlGaInN material system allows for laser diodes to be fabricated over a wide range of wavelengths from the u.v. to the visible. We report our latest results on a range of AlGaInN diode-lasers targeted to meet the linewidth, wavelength and power requirements suitable for quantum sensors such as optical clocks and cold-atom interferometry systems. This includes the [5s²S_1/2-5p²P_1/2] cooling transition in strontium+ ion optical clocks at 422 nm, the [5s₂¹S₀-5p¹P₁] cooling transition in neutral strontium clocks at 461 nm and the [5s²s_1/2 – 6p²P_3/2] transition in rubidium at 420 nm. Several approaches are taken to achieve the required linewidth, wavelength and power, including an extended cavity laser diode (ECLD) system and an on-chip grating, distributed feedback (DFB) GaN laser diode.

In our previous work we described quantized computation using Horn clauses and based the semantics, dubbed as entanglement semantics as a generalization of denotational and distribution semantics, and founded it on quantum probability by exploiting the key insight classical random variables have quantum decompositions. Towards this end we built a Hilbert space of H-interpretations and a corresponding non commutative von Neumann algebra of bounded linear operators. In this work we extend the formalism using second-quantized Horn clauses that describe processes such as Heisenberg evolutions in optical circuits, quantum walks, and quantum filters in a formally verifiable way. Our goal is to build a model of computation based on logic via Currry-Howard correspondence. Towards this end we can think of completely positive *-unital maps of Horn clauses as function types representing modus ponens (equation (19)). Recursions that result from inductive reasoning has a quantum analogue in terms of sequence of *-homomorphisms induced by completely positive *-unital maps (equation (18)). We base our system on a measure theoretic approach to handle infinite dimensional systems and demonstrate the expressive power of the formalism by casting an algebra used to describe interconnected quantum systems (QNET) in this language. The variables of a Horn clause bounded by universal or existential quantifiers can be used to describe parameters of optical components such as beam splitter scattering paths, cavity detuning from resonance, strength of a laser beam, or input and output ports of these components. Prominent clauses in this non commutative framework are Weyl predicates, that are operators on a Boson Fock space in the language of quantum stochastic calculus, martingales and conjugate Brownian motions compactly representing statistics of quantum field fluctuations. We formulate theorem proving as a quantum stochastic process in Heisenberg picture of quantum mechanics, a sequence of goals to be proved, using backward chaining.

A scalable model for a distributed quantum computation is a challenging problem due to the complexity of the problem space provided by the diversity of possible quantum systems, from smaller quantum devices to large-scale quantum computers. Here, we define a scalable distributed model of gate-model quantum computation in near-term quantum systems.