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The unique features of the hybrid quantum-classical computing model implied by the specification of OpenQASM 3.0 motivate new approaches to quantum program verification. We implement a typed QASM 3.0 parser in TypeScript to enable implementations of verification and validation software, compilers and more. We also propose that a formal treatment of OpenQASM 3.0's type system in type theory notation may further facilitate formal verification. We highlight advancements in hybrid quantum-classical computing since the Quantum Hoare Logic to this end.

IBM has developed a quantum assembly (QASM) language particular to gate model quantum computing since 2017 [CBSG17]. Version 3.0 which adds timing, pulse control, and gate modifiers is currently undergoing finalization in 2023 [CJA+21]. In a similar vein, Pakin of Los Alamos National Laboratory published a quantum macro assembler (QMASM) for D-Wave quantum annealers in 2016 [Pak16]. This assembler specifically targets quantum annealers like D-Wave's. A comparable technology that targets continuous-variable (CV) quantum computing is the Blackbird language developed by Xanadu since 2018 [KIQ+19]. We implement parsers for each of these languages in TypeScript with a singular approach. In the cases of Blackbird and QMASM these are the first parser implementations that are web compatible and so bring these languages to a new audience and to new runtimes. This makes the parsing and execution of QMASM, QASM and Blackbird possible in web and mobile environments that don't have access to heavy compile toolchains, enabling adoption and scientific research.

One of the most exciting quantum emulation [1] breakthroughs was the first analog signal-based emulation of a universal quantum computer [2]. This yielded a very interesting paper, but no practical use - even for theorists. The reason for this was that a signal duration of the approximate age of the universe (13.77 billion years) could accommodate only about 95 qubits. We propose a new scheme with the following properties: 1) a pair of oscillators or sinusioidal wave sources must be sufficient to emulate n superimposed states with the ability to be identifiably mixed or entangled, 2) the time required to perform a measurement of a state must not scale poorly with the complexity of the state, 3) a fixed set of hardware components must be sufficient to emulate a system of a significant number of qubits, and 4) at least as much must be knowable about an emulated quantum state as is expected to be measurable in a theoretical quantum computing system. We achieve a design whose time complexity scales favourably based on a new method of encoding quantum information into classical signals, but only anticipate the feasibility of encodings of up to 20 qubits with modern electrical hardware.

We suggest that the Quantum Honest Byzantine Agreement (QHBA) protocol [1] essentially reduces consensus to coincidence. The volume of coincidence is the parameter that drives a receiver to echo its input. A lack of coincidence results in no output from a receiver. This is a similar mechanism therefore to the learning mechanism in cognitive modular neural architectures like Haikonen's architecture [2]. We introduce a simple feedback mechanism and quantum neuron to realize a hybrid quantum / classical machine learning network of simple nodes.

Blockchain technology is facing critical issues of scalability, efficiency and sustainability. These problems are necessary to solve if blockchain is to become a technology that can be used responsibly. Useful quantum computers could potentially be developed by the time that blockchain will be widely implemented for mission-critical work at financial and other institutions. Quantum computing will not only cause challenges for blockchain, but can also be harnessed to better implement parts of blockchain technologies including cryptocurrencies. We review the work that has been done in the area of quantum blockchain and hybrid quantum-classical blockchain technology and discuss open questions that remain., Comment: 27 pages, 1 figure