Commentary and a selection of the most important recent news, articles, and papers about Quantum.
Today’s Brief Commentary
Plastic glass.
Jumbo shrimp.
Open secret.
These are all examples of oxymorons, phrases whose first halves seem to be the opposite of the second. I read another one over the weekend:
Quantum computing classical hardware.
To be fair, the vendor was very clear that they sold classical hardware on which you can run optimized simulations of quantum circuits, but the phrase struck me as odd.
The word “simulator” is used in several ways when attached to “quantum computing.” For example, it could mean that the programming paradigm works well to translate models of physical systems onto a quantum system and then compute with them or see how they develop. The word “Hamiltonian,” meaning a mathematical representation of the energy state of a system, often pops up in such use cases.
Another example is when we build quantum circuits from gates such as X, Y, Z, H, and CNOT and then execute them on classical hardware using classical software. We also call this paradigm “digital” or “discrete variable.” It’s a nice undergraduate project to write a small quantum circuit simulator.
There are more or less efficient, accurate, and complex ways of writing circuit simulators. I cover this topic in section 11.8 of my book Dancing with Qubits, Second Edition. If you have a particular circuit form in mind, you can simulate more qubits because you don’t have to build in all the general machinery, and you can optimize the specific gate configurations.
Quantum circuit simulators are good tools for education, research, and experimentation, but we already have quantum computers with far too many qubits to be fully simulated. A simulator can speed up the development and debugging of small portions of quantum circuits, so they will not go away, even once we have large systems providing Practical Quantum Advantage.
As the end-of-the-year holidays approach for many of you, I hope you can get some time off and have true, versus working, vacations. (See what I did there?)
General News, Articles, and Analyses
Bringing the Power of Tabletop Precision Lasers for Quantum Science to the Chip Scale
Author: Sonia Fernandez
(Friday, December 13, 2024) “But what if these atomic applications could be lifted from their current confines in labs and on benchtops? This advancement is at the heart of the effort at UC Santa Barbara engineering professor Daniel Blumenthal’s lab, where his team seeks to recreate the performance of these lasers on lightweight devices that can fit in the palm of your hand.”
Financial and Earnings Announcements
Rigetti Computing Announces Pricing of $100 Million Registered Direct Offering of Common Stock Priced At-The-Market Under Nasdaq Rules
(Tuesday, November 26, 2024) “Rigetti Computing, Inc. (Nasdaq: RGTI) (“Rigetti” or the “Company”), a pioneer in full-stack quantum-classical computing, today announced that it has entered into securities purchase agreements with two institutional investors for the purchase and sale of 50,000,000 shares of the Company’s common stock, par value $0.0001 per share, at a purchase price of $2.00 per share, pursuant to a registered direct offering priced at-the-market under Nasdaq rules, resulting in gross proceeds of approximately $100 million, before deducting placement agent commissions and other offering expenses.”
D-Wave Announces Successful Completion of $175 Million At-the-Market Equity Offerings
(Thursday, December 12, 2024) “D-Wave Quantum Inc. (NYSE: QBTS) (“D-Wave” or the “Company”), a leader in quantum computing systems, software, and services, and the world’s first commercial supplier of quantum computers, today announced that it has successfully completed sales of $175 million in gross proceeds of its common stock pursuant to its previously disclosed $100 million and $75 million “at-the-market” equity offering programs (the “ATM Programs”). The $75 million ATM Program, implemented on Monday, December 9th , was completed at an average price per share of $4.8149. Over that same three-day period, D-Wave stock traded at a Volume Weighted Average Price (“VWAP”) of $4.6625 (per Bloomberg). The Company expects to end the current fiscal 2024 fourth quarter with at least $160 million in cash. The funds were used, and will continue to be used, for working capital and capital expenditures in support of D-Wave’s ongoing technical development efforts and business operations.”
Newsletter Editions
Quantum’s Shift to Quality | by Brian Lenahan
https://brianlenahan.substack.com/p/quantums-shift-to-quality
Author: Brian Lenahan
(Monday, December 16, 2024) “The quantum technology industry is undergoing a pivotal shift from prioritizing the sheer number of qubits to emphasizing their quality, driven by the challenges of achieving practical, fault-tolerant quantum computing. This transition reflects advancements and strategic shifts in areas such as error correction, roadmaps, logical qubits, and coherence.”
Quantum Computing
Oxford Instruments NanoScience installs dilution refrigerators in the NQCC’s purpose-built research labs | Oxford Instruments
(Wednesday, December 11, 2024) “Oxford Instruments NanoScience has installed three ProteoxMX dilution refrigerators at the National Quantum Computing Centre (NQCC), the UK’s national lab for quantum computing at their Harwell Campus. The systems will be used by the NQCC’s research team, who are developing hardware architectures based on superconducting circuits.”
The Gestalt IT Rundown: December 11, 2024
Commentary:
I speak at the 11:16 time mark in the video.(Wednesday, December 11, 2024) “Google released a paper this week that showed how far quantum computing has come in the past few years. The company was able to increase the number of hardware quantum bits, or qubits, dedicated to error correction in order to create a 105-qubit cluster …”
Quobly Forges Strategic Collaboration with STMicroelectronics to Accelerate its Quantum Processor Manufacturing for Large-Scale Quantum Computing Solutions
Commentary:
Quobly makes silicon spin qubits, the most popular quantum modality after superconducting.(Thursday, December 12, 2024) “Quobly, a cutting-edge quantum computing startup, today announced a transformative collaboration with STMicroelectronics, a global semiconductor leader serving customers across the spectrum of electronics applications, to produce quantum processor units (QPUs) at scale. By leveraging STMicroelectronics’ advanced FD-SOI semiconductor process technologies, this collaboration is set to make large-scale quantum computing feasible and cost-effective, positioning both companies at the forefront of next-generation computing technologies.”
Gov. Pritzker Announces Collaboration with IBM to Build New National Quantum Algorithm Center
(Friday, December 13, 2024) “Today, Governor JB Pritzker joined IBM’s Chairman and CEO Arvind Krishna, University of Chicago President Paul Alivisatos, Illinois Quantum and Microelectronics Park (IQMP) CEO Harley Johnson, and industry stakeholders to announce the new National Quantum Algorithm Center. This groundbreaking Center will be fueled by IBM’s next-generation, modular quantum computer (“IBM Quantum System Two”), and will aim to advance the exploration of quantum-centric supercomputing across industries, furthering Illinois’ status as a leader in emerging technology and a global quantum computing capital.”
Quantum Computing | Technical
[2412.07969] AC/DC: Automated Compilation for Dynamic Circuits
https://arxiv.org/abs/2412.07969
Authors: Niu, Siyuan; Kokcu, Efekan; Mitra, Anupam; Szasz, Aaron; Hashim, Akel; Kalloor, Justin; de Jong, Wibe Albert; Iancu, Costin; and Younis, Ed
(Tuesday, December 10, 2024) “Dynamic quantum circuits incorporate mid-circuit measurements and feed-forward operations originally intended to realize Quantum Error Correction. This paradigm has recently been utilized to prepare certain states and long-range entangling gates as well as reduce resource overhead in quantum algorithms such as Quantum Fourier Transformation and Quantum Phase Estimation. In this paper, we present a novel framework for generating dynamic quantum circuits that automatically prepare any state or unitary operator. This procedure is powered by numerical optimization-based circuit synthesis methods. The first contribution is introducing optimization objective functions incorporating mid-circuit measurement and feed-forward operations. The second contribution is incorporating these into a popular open-source quantum circuit synthesis framework. We demonstrate the generation of dynamic circuits for state preparation, long-range entangling gates, circuit optimization, and the application of dynamic circuits to lattice simulations. The resulting circuits are validated through simulation and execution on quantum hardware. Furthermore, we perform noise analysis to explore the impact of different error ratios in mid-circuit measurements and gate errors, identifying scenarios where dynamic circuits offer the most significant benefits. The dynamic circuits generated by our framework show substantial improvements in reducing circuit depth and, in some cases, the number of gates required. To our knowledge, this is the first practical procedure to generate dynamic quantum circuits. Our objective functions are independent of the underlying synthesis framework and can be easily reused. This framework opens new possibilities for circuit generation and optimization methods, highlighting the potential of dynamic circuits to enhance the performance of quantum algorithms on near-term quantum computers.”
[2412.09239] Application of quantum annealing for scalable robotic assembly line optimization: a case study
https://arxiv.org/abs/2412.09239
Authors: Willmann, Moritz; Albus, Marcel; Schnabel, Jan; and Roth, Marco
Commentary:
Note the last sentence.(Thursday, December 12, 2024) “The even distribution and optimization of tasks across resources and workstations is a critical process in manufacturing aimed at maximizing efficiency, productivity, and profitability, known as Robotic Assembly Line Balancing (RALB). With the increasing complexity of manufacturing required by mass customization, traditional computational approaches struggle to solve RALB problems efficiently. To address these scalability challenges, we investigate applying quantum computing, particularly quantum annealing, to the real-world based problem. We transform the integer programming formulation into a quadratic unconstrained binary optimization problem, which is then solved using a hybrid quantum-classical algorithm on the D-Wave Advantage 4.1 quantum computer. In a case study, the quantum solution is compared to an exact solution, demonstrating the potential for quantum computing to enhance manufacturing productivity and reduce costs. Nevertheless, limitations of quantum annealing, including hardware constraints and problem-specific challenges, suggest that continued advancements in quantum technology will be necessary to improve its applicability to RALB manufacturing optimization.”
Quantum Networking | Technical
[2412.09299] An Optical Interconnect for Modular Quantum Computers
https://arxiv.org/abs/2412.09299
Authors: Sakuma, Daisuke; Taherkhani, Amin; Tsuno, Tomoki; Sasaki, Toshihiko; Shimizu, Hikaru; Teramoto, Kentaro; Todd, Andrew; Ueno, Yosuke; Hajdušek, Michal; ; …; and Nagayama, Shota
Commentary:
‘Modular’ is the key word here. I would insert neutral atoms between ion traps and superconducting in the last sentence in terms of ease of implementation.(Thursday, December 12, 2024) “Much like classical supercomputers, scaling up quantum computers requires an optical interconnect. However, signal attenuation leads to irreversible qubit loss, making quantum interconnect design guidelines and metrics different from conventional computing. Inspired by the classical Dragonfly topology, we propose a multi-group structure where the group switch routes photons emitted by computational end nodes to the group’s shared pool of Bell state analyzers (which conduct the entanglement swapping that creates end-to-end entanglement) or across a low-diameter path to another group. We present a full-stack analysis of system performance, a combination of distributed and centralized protocols, and a resource scheduler that plans qubit placement and communications for large-scale, fault-tolerant systems. We implement a prototype three-node switched interconnect and create two-hop entanglement with fidelities of at least 0.6. Our design emphasizes reducing network hops and optical components to simplify system stabilization while flexibly adjusting optical path lengths. Based on evaluated loss and infidelity budgets, we find that moderate-radix switches enable systems meeting expected near-term needs, and large systems are feasible. Our design is expected to be effective for a variety of quantum computing technologies, including ion traps and superconducting qubits with appropriate wavelength transduction.”
