Hear from Krysta Svore, Principal Research Manager of Microsoft Quantum, on how creating resilient logical qubits is crucial in developing quantum computers. Currently, according to Krysta Svore, the industry is approaching Level 2.

Atom Computing, a Boulder-based company, has developed a scalable, high-fidelity method for midcircuit measurement in quantum computing. The team used a single-species tweezer array of neutral 171Yb atoms to perform nondestructive state-selective and site-selective detection. This allows a subset of qubits to be measured while causing only percent-level errors on the remaining qubits. The technique also demonstrated the ability to reuse ancilla qubits and perform conditional refilling of ancilla sites to correct for occasional atom loss, while maintaining the coherence of data qubits. The research was led by M. A. Norcia and B. J. Bloom.

Qubits, or quantum bits, are the fundamental units of quantum information. Unlike classical bits, which can be either 0 or 1, qubits can exist in a superposition of both states simultaneously. This property, along with quantum entanglement (where qubits become interconnected and the state of one instantly affects the state of another, regardless of distance). The principles of quantum mechanics govern the behavior of qubits, and harnessing their unique properties gives quantum computers their potential power.

Insider Brief

• Silicon qubits have long coherence times and are compatible with advanced semiconductor manufacturing techniques.
• These qubits also face challenges, such as charge noise and valley splitting.
• Researchers at the University of Rochester, University at Buffalo, SUNY Stony Brook, NY Creates, University of California, Los Angeles and Lawrence Livermore National Laboratory are using grant funds to find ways to overcome silicon qubit challenges.
• Image: University of Rochester physicist John Nichol is exploring ways to overcome some shortcomings of otherwise promising silicon spin qubits. (Mark Garlick / Getty Images Science Photo Library)

PRESS RELEASE — Quantum computers harness quantum mechanics to perform computations and solve problems beyond the capabilities of classical computers. While a regular computer consists of billions of transistors, called bits, quantum computers are based on quantum bits, also known as qubits.

In the quest to build powerful quantum computers, one type of qubit has shown exceptional promise: silicon spin qubits. These qubits not only have long coherence times but are also compatible with advanced semiconductor manufacturing techniques. Despite this promise, the material used in silicon spin qubits creates recurring challenges for researchers. These include:

• Charge noise, or erratic fluctuations in the electrostatic environment surrounding the qubits, making them unstable
• Valley splitting, which creates quantum-dot energy levels that can get too close and cause unwanted complications
• Spatial variations in electron g-factor, which can lead to difficulty controlling qubits

To overcome these challenges, the US Air Force Office of Scientific Research (AFOSR) has awarded more than $6.7 million to a multidisciplinary team of experts in materials characterization and modeling, silicon fabrication, and quantum experiments. Led by researchers at the University of Rochester, the team includes collaborators at the University at Buffalo; SUNY Stony Brook; NY Creates; University of California, Los Angeles; and Lawrence Livermore National Laboratory.

“We are taking a materials-first approach to discovering the underlying causes of the challenges with silicon spin qubits,” says John Nichol, an associate professor of physics at Rochester and the primary investigator on the project.

AFOSR funds high-risk basic research that has the potential to profoundly impact the nation’s technological progress, in areas including the development of stable and powerful quantum computers. The office’s funding of a partnership between academia, a national laboratory, and an innovation hub is key to making advances in quantum computing, according to Nichol.

“This team has the required expertise to investigate correlations and causation in silicon spin qubits and ultimately accelerate progress through materials development in this platform,” he says.

Researchers Michael Kuehn and Davide Vodola at BASF, the world's largest chemical company, are using quantum computing to study NTA, a compound used to remove toxic metals from wastewater. They have simulated the equivalent of 24 qubits, the processing engines of a quantum computer, on GPUs and recently ran their first 60 qubit simulations on NVIDIA’s Eos H100 Supercomputer. The simulations are run on NVIDIA CUDA Quantum, a platform for programming CPUs, GPUs, and quantum computers. BASF's quantum computing initiative, launched in 2017, is also developing use cases for machine learning, logistics, and scheduling.

Quoherent Inc., a company developing quantum processors that operate at room temperature, has secured $4.7 million in Series Seed financing. The funding round was led by Morpheus Ventures and included Draper Associates, Khosla Ventures, and Alpha Edison. The funds will be used to accelerate the development of Quoherent's "third-wave" solid state quantum qubits. The company's CEO, Roberto DiSalvo, believes this will enable them to deliver industry-changing quantum processors. Quoherent is the result of a decade-long research collaboration between its founders and the Wake Forest Center for Nanotechnology and Quantum Materials.

D-Wave a leading quantum computing company, has announced successful Quantum Error Mitigation (QEM) in its Advantage2 annealing quantum computing prototype. The QEM techniques reduce errors in quantum simulations, leading to results consistent with the quantum system maintaining its quantum state for a significantly longer time. This advancement is expected to improve performance in the forthcoming Advantage2 system and future processors. The research, led by Mohammad Amin, marks D-Wave's first experimental demonstration of Zero-Noise Extrapolation, a practical QEM technique. This could help tackle complex problems in scientific and machine learning applications.

Professors Angela Kou, Pinshane Huang, Wolfgang Pfaff, and Andre Schleife from the University of Illinois Urbana-Champaign have received a nearly $1 million grant from the Air Force Office of Scientific Research. The funding is for a project to identify and address defects in Josephson junctions, a key component in superconducting qubits used in quantum computing. The team will use transmission electron microscopy to study the defects and losses in the junctions. The goal is to improve the control and predictability of these junctions, which could help advance the field of quantum computing.

Physicists at MIT have successfully trapped electrons in a pure crystal, achieving an electronic "flat band" in a three-dimensional material for the first time. This state allows electrons to behave in coordinated, quantum ways, potentially leading to superconductivity and unique forms of magnetism. The crystal's atomic geometry, inspired by the Japanese art of basket-weaving known as "kagome", enables this trapping of electrons. The researchers, including Joseph Checkelsky, Joshua Wakefield, Mingu Kang, Paul Neves, and Dongjin Oh, believe this discovery could lead to ultraefficient power lines, supercomputing quantum bits, and faster, smarter electronic devices.

Insider Brief

• A team from Tokyo Institute of Technology and RIKEN has published a study in Nature Physics revealing significant noise correlations between pairs of silicon spin qubits, which could impact the development of scalable quantum processors.
• The research focused on measuring and quantifying the correlations of noise that may impair the performance of quantum processors by increasing error rates, a crucial aspect considering the millions of qubits required for a functional quantum computer.
• Utilizing a novel Bayesian estimation technique, the researchers confirmed strong noise correlations that persist over distance, underscoring the need for new methods to manage such noise in dense qubit arrays for future semiconductor-based quantum computing systems.

UNIVERSITY RESEARCH NEWS — TOKYO/November 3, 2023 — A research team at the Tokyo Institute of Technology and RIKEN recently set out to reliably quantify the correlations between the noise produced by pairs of semiconductor-based qubits, which are very appealing for the development of scalable quantum processors. Their paper, published in Nature Physics, unveiled strong interqubit noise correlations between a pair of neighboring silicon spin qubits.

“A useful quantum computer would practically require millions of densely packed, well-controlled qubits with errors not only small but also sufficiently uncorrelated,” Jun Yoneda, one of the researchers who carried out the study, told Phys.org. “We set out to address the potentially serious issue of error correlation in silicon qubits, as they have become a compelling platform for large quantum computations otherwise.”

Fabricating highly performing quantum processors based on many closely positioned silicon qubits has so far proved challenging. These systems would exhibit noise that is correlated between different qubits. This reduces the devices’ fault tolerance, increasing their error rate and thus impairing their performance.

As part of their recent study, Yoneda and his colleagues set out to explore the extent of these interqubit noise correlations, in the hope of informing the future development of semiconductor-based quantum computing systems. To do this, they analyzed and tried to quantify the correlation between the noise seen by two silicon-based qubits that were placed 100 nm away from each other.

“Errors in silicon spin qubits are dominated by fluctuations of the qubit energy, that is, the energy difference between the spin-up and -down states,” Yoneda explained. “We measured the simultaneous time evolution of qubit energies and assessed the ‘degree of similarity’ between the two time traces via a quantity called the cross power spectral density.”

The researchers subsequently used a Bayesian estimation technique they developed as part of their previous research work, which is designed to give the probability distributions of cross power spectral densities. This technique allowed them to validate the statistical relevance of the correlations they observed, confirming that the two qubits were subject to strongly correlated noise.

“We observed strong noise correlations between silicon qubits — with a correlation strength as large as 0.7 at some frequencies,” Yoneda said. “Such correlations due to electrical noise are unlikely to decay quickly with distance, so we are now keenly aware that error correlation needs to be taken seriously in dense qubit arrays in silicon. We also showed that noise correlation analysis provides novel insights into the source of qubit noise.”

The statistical methods employed by this team of researchers is unique and powerful, as contrarily to conventional approaches, it requires no prior knowledge of the auto-spectrum (e.g., 1/f) to assess and quantify qubit noise. Overall, the findings of this recent work confirm the challenges associated with noise correlation between closely situated silicon qubits, highlighting the need to devise new approaches to suppress or mitigate noise in semiconductor-based quantum computers.

“Our future research will include investigating how far the correlation will extend in a qubit array, leveraging the methods of including cross correlations in noise analysis that we pioneered here experimentally,” Yoneda added. “This is a critical question concerning fault-tolerance, as well as understanding of the noise source.”

Written by Ingrid Fadelli , Phys.org

Featured image: Characterization of qubit error correlation in a silicon qubit array. Credit: Yoneda et al

Quantum computing company IonQ reports Q3 2023 revenues of $6.1 million, a 122% increase from the previous year. The company also announced a $25.5 million sale of its Quantum Networking System to the US Air Force Research Lab. IonQ's CEO, Peter Chapman, highlighted the company's achievement of $100 million in cumulative bookings within three years of commercialization. The company also unveiled two new quantum computers, IonQ Forte Enterprise, and IonQ Tempo, and aims to achieve a 64-qubit system by the end of 2025.

D-Wave, reported a 50% increase in revenue to $2.6 million for Q3 2023. The company's cash balance reached $53.3 million, the highest in its history. CEO Dr. Alan Baratz highlighted the company's growth in customer bookings and commercial revenue. D-Wave has signed new agreements with BBVA, QuantumBasel, NTT Docomo, Poznan Superconducting and Networking Center, and Satispay. The company is also exploring integrating its quantum technology with machine learning. D-Wave has made significant progress in the development of high-coherence qubits and quantum error mitigation.

IQM Quantum Computers, a Finnish company, has unveiled its quantum computing platform, "IQM Radiance". The platform comes in two versions: a 54-qubit system available in 2024, and a 150-qubit system available from 2025. The platform is designed for businesses, high-performance computing centres, data centres, and government agencies. It aims to provide quantum computing capabilities for real-life use cases, including machine learning, cybersecurity, energy grid optimisation, and drug research. Dr. Jan Goetz, CEO of IQM, believes this is the right time for businesses to invest in quantum computing to gain a competitive edge.

Quantum computing company IonQ has appointed Margaret Arakawa as Chief Marketing Officer and Kurt Kennett as Vice President of Software. Arakawa, who has previously worked at Microsoft, Outreach, and Fastly, will play a key role in IonQ's growth strategy. Kennett, with experience from Microsoft, General Electric, and Nintendo, will lead software operations for IonQ's systems. The appointments follow a year of growth for IonQ, including a $25.5M deal with the US Air Force Research Lab and achieving a technical milestone on a barium platform. IonQ's quantum systems are available through Amazon Braket, Microsoft Azure, and Google Cloud.

Microsoft and Photonic Inc. have announced a strategic collaboration to advance quantum networking and computing. The partnership will combine Photonic's spin-photon architecture, which supports quantum communication over standard telecom wavelengths, with Microsoft's Azure infrastructure. The aim is to integrate quantum networking capabilities into everyday operating environments. Jason Zander, Executive Vice President of Strategic Missions and Technologies at Microsoft, and Dr. Stephanie Simmons, founder and Chief Quantum Officer of Photonic, highlighted the potential of the collaboration to accelerate scientific discovery and innovation in quantum computing. The partnership will focus on three stages of quantum networking, including the development of a reliable quantum repeater.

Insider Brief

• ETH Zurich is leading efforts that focus on the pivotal challenge of connecting two error-corrected qubits.
• The project involves collaboration with MIT, Forschungszentrum Jülich, Université de Sherbrooke, Zurich Instruments, Atlantic Quantum, and the ETHZ-PSI Quantum Computing Hub at the Paul Scherrer Institute.
• Connecting error-corrected qubits is considered a fundamental step in advancing quantum computing technology.
• Image: ETH Zurich

ETH Zurich is playing a crucial role in two quantum computing projects, both financed by IARPA, a US-based research funding agency, according to a news release on the university’s website. These projects, which are being funded with up to $40 million, focus on the pivotal challenge of connecting two error-corrected qubits—a fundamental step in advancing quantum computing technology.

The two projects supported by IARPA are SuperMOOSE and MODULARIS. SuperMOOSE, led by ETH Professor Andreas Wallraff, involves collaboration with MIT, Forschungszentrum Jülich, Université de Sherbrooke, Zurich Instruments, Atlantic Quantum, and the ETHZ-PSI Quantum Computing Hub at the Paul Scherrer Institute. Meanwhile, MODULARIS is coordinated by the University of Innsbruck, with ETH Professor Jonathan Home’s group contributing.

Both projects aim to entangle two logical qubits and transfer quantum states between them, employing different technological approaches.

“If we manage to connect two error-​corrected qubits with one another, we’ll have laid the groundwork for future quantum computers that can then be used to tackle a broad range of tasks,” Wallraff said in the release.

Eye Toward Practical Applications

Quantum computers have long been a topic of interest due to their potential to solve complex computational problems that are currently beyond the reach of traditional computers. However, the practical application of quantum computers has been hindered primarily by their vulnerability to errors. ETH Zurich has made notable progress in this area, with two of its research groups successfully demonstrating error correction in quantum systems, according to the realse. This achievement involved using a chip with 17 physical quantum bits (qubits) to create a single logical qubit, with a division of labor between the qubits for error correction and computational tasks.

The ETH team is focusing on superconducting components, while the Innsbruck team uses ion traps. This diversity in approach highlights the multifaceted nature of quantum computing research. Over the next four years, both teams’ progress and results will be scrutinized and shared in scientific journals. Success in connecting two error-corrected qubits will set a foundation for quantum computers capable of handling a wide array of tasks.

However, these projects will have its challenges. Building a functional quantum computer would one day require linking not just two but potentially thousands of logical qubits. This complex, time-consuming, and costly process underscores the need for international collaboration.

The involvement of ETH Zurich in these two significant projects underlines its leadership in quantum research, according to Christian Wolfrum, Vice President for Research at ETH Zurich, who expressed satisfaction with IARPA’s support, emphasizing the importance of Switzerland’s involvement in Horizon Europe.

“IARPA’s decision to fund not one but two projects in which ETH Zurich is involved confirms our university’s leading position in this vital research area,” Wolfrum said in the release. “It’s now crucial that Switzerland be an associated country in Horizon Europe as soon as possible so that our researchers can also participate in the EU’s flagship quantum programme.”

The "Quantum 301: Quantum Computing with Semiconductor Technology" EdX program offers advanced courses on semiconducting quantum technologies, focusing on Germanium qubits. These qubits, a new type of semiconducting qubits, have shown rapid progress since their development in 2018. The program, a collaboration between several parties with state-of-the-art facilities, provides insight into the physics behind Germanium qubits, their advantages, challenges, and the electrical components needed for their control. It also covers the integration of machine learning into qubit tuning and control workflows. Prior knowledge about fabrication methods is recommended for full benefit.

Microsoft's Azure Quantum has developed a hybrid quantum supercomputer that combines quantum and classical computing to solve complex problems. The system requires at least one million stable and controllable qubits, and uses error correction to maintain stability. Microsoft's unique topological qubit design aids this stability. The hybrid nature of the supercomputer allows for the integration of quantum and classical computing. Researchers from Microsoft and Quantinuum have successfully run Magic State Distillation and Repeat-Until-Success algorithms on the Azure Quantum system. The system uses Quantum Intermediate Representation to represent quantum and classical logic, optimising program logic.