Keeping up with quantum computing announcements is increasingly challenging. Today, IBM issued a paper outlining a technique for error mitigation in today’s noisy QCs. Last week IonQ posted a paper benchmarking its ion trap system and declared, “our system outperforms all other currently available hardware” while a Microsoft-led group announced formation of the Northwest Quantum Nexus. Yesterday D-Wave Systems announced expansion of its web portal Leap during its User Meeting (Qubits Europe 2019, Milan) which includes industry heavyweights such as BMW, G.E. Research, and Volkswagen.

Widespread use of practical quantum computing may be years away, but the vanguard is pushing steadily forward. Here are bullets for five recent quantum announcements with a bit more information on a few them below:

• IBM keeps chipping away at obstacles stalling real-world use of the current crop of noisy intermediate scale quantum computers. Its paper (Error mitigation extends the computational reach of a noisy quantum processor) claims the protocol IBM developed “will enable substantial improvements in the capabilities of near-term quantum computing hardware.” In this instance two or more wrongs can help equal a right. More below.
• IonQ edges into early benchmark skirmishes. In its paper (Benchmarking an 11-qubit quantum computer) the company says its ion trap-based system achieved, “average single-qubit gate fidelities of 99.5%, [and] average two-qubit-gate fidelities of 97.5%.” IonQ contends the algorithms it used “serve as excellent benchmarks for any type of quantum hardware.” Recall that IBM touted Quantum Volume as its favored metric of choice just three weeks ago.
• Microsoft, PNNL, and UWashington Join Forces. Last week, this trio announced formation of the Northwest Quantum Nexus, “a coalition of research and industrial organizations in the Pacific Northwest and neighboring regions with the goal of advancing Quantum Information Sciences (QIS) research and developing a QIS-trained workforce.”
• D-Wave Systems reports “33 new countries includ[ing] all 28 member states of the European Union, Japan, Iceland, Liechtenstein, Norway, and Switzerland” now have access to Leap, which D-Wave characterizes as “the only cloud-based service to provide real-time access to a live quantum computer, as well as open-source development tools, interactive demos, educational resources.”
• Accredited Standards Committee X9, long-time tracker and standards association for the financial industry, issued two reports, a white paper (X9 Report Quantum Computing Risks to the Financial Services Industry) examining risks posed by QC and a technical report (X9 Technical Report TR-50 – Quantum Techniques in Cryptographic Message Syntax).

IonQ Charges into Quantum Race

Let’s start with IonQ, perhaps lesser known than quantum efforts by IBM, Microsoft, and D-Wave. It was founded in 2016 by a pair of distinguished quantum computing researchers – Chris Monroe (University of Maryland and Joint Quantum Institute) and Jungsang Kim (Duke University) – to take ion trap quantum computing from the lab to market. Monroe (CEO) and Kim (CSO) are leveraging technology they helped developed and have licensed from UM and Duke.

Most of us are more familiar with semiconductor-based quantum computing technology which dominates the quantum computing landscape. Ion trap technology has also been around for a long time and NIST (National Institute of Standards and Technology) has long experimented with it, not least for use in atomic clocks. The ion traps used in quantum computing are not so different from the ion traps used in spectrometry. Broadly, the technology involves trapping ions in an electromagnetic field and using them as qubits. While “gate switching” times are slower than semiconductor approaches, memory times are superior using ions traps.

Here’s a bit more on how the IonQ system works: “Our qubit register is comprised of a chain of trapped 171Yb+ ions, spatially confined near a microfabricated surface electrode trap. For this work, we load 13 ions, the middle 11 of which are used as qubits. The two end ions allow for a more uniform spacing of the central 11 ions. The ions are laser-cooled close to their motional ground state using a combination of Doppler and resolved sideband cooling. We encode quantum information into the hyperfine sublevels…At the beginning of each computation, each qubit is initialized to |0⟩via optical pumping with high accuracy. After qubit operations (described below), we read out the state of all of the qubits simultaneously by directing laser light resonant with the 2S1/2 |F = 1⟩to 2P1/2 transition, imaging each ion onto a detector and thresholding the photon counts to determine if each qubit was in the |1⟩(spin up) or |0⟩(spin down) state.” (See figure on right, click to enlarge.)

Monroe commented in the announcement, “The real test of any computer is what can it do in a real-world setting. We challenged our machine with tough versions of two well-known algorithms that demonstrate the advantages of quantum computing over conventional devices. The IonQ quantum computer proved it could handle them. Practical benchmarks like these are what we need to see throughout the industry.”

This is excerpted from the abstract on the benchmark performance:

“To illustrate the capabilities of this universal platform and provide a basis for comparison with similarly-sized devices, we compile the Bernstein-Vazirani (BV) and Hidden Shift (HS) algorithms into our native gates and execute them on the hardware with average success rates of 78% and 35%, respectively. These algorithms serve as excellent benchmarks for any type of quantum hardware, and show that our system outperforms all other currently available hardware.”

The Bernstein-Vazirani and Hidden Shift algorithms used in this experiment instruct a computer to find a hidden number out of a set of possible numbers. The company reported, “IonQ has solved for all possible 1024 hidden numbers with their 11-qubit machine, a more difficult task than has been attempted before on a quantum computer. Each test is based on a formula that a conventional computer can only solve by brute force…Quantum computers, in theory, can find these solutions in a single calculation by measuring all possible outputs simultaneously.”

It will be interesting to watch how ion trap quantum computing advances. Last August, NSF launched an ambitious program, Software Tailored Architecture for Quantum Design (STAQ), whose goal is to build a 64-bit ion trap QC and associated software stack capable of tackling problems classical computers struggle with. (For more information see HPCwire article, STAQ(ing) the Quantum Computing Deck)

IBM – Two Wrongs Make a Right…Sort of

IBM’s recent work tackles one of the thorniest problems in quantum computing, error correction, or in this case error mitigation. IBM has come up with a workaround that shows promise and is presented in a paper published today in Nature (Error mitigation extends the computational reach of a noisy quantum processor) and discussed in an IBM blog by Jay Gambetta, IBM Fellow, and Abhinav Kandala, research staff member, who describe the problem very well.

“Even at the extreme cold temperatures of a dilution refrigerator where the quantum processors operate, our physical computing elements, superconducting qubits, have coherence times on the order of a few hundred microseconds at best, which sets the timescales over which quantum information is lost,” they write. “While a major challenge to advancing quantum computers today involves increasing these qubit coherence times, the end goal is to build a fully fault tolerant quantum computer capable of detecting and correcting errors. However, these architectures are likely several years away.”

IBM takes a perhaps counterintuitive approach in which two wrong answers – actually many wrong answers – can act as a guide to the correct answer. “We show that repeating the computation at varying levels of noise lets us estimate what the quantum computer would calculate in the absence of noise. To do this involves a bit of a “stretch” – the microwave pulses used to perform quantum operations on the qubits are stretched in time in order to controllably amplify the noise. The error mitigation technique dubbed “zero-noise extrapolation”, is readily accessible for existing quantum computers since it doesn’t require any additional hardware modifications,” write Gambetta and Kandala. (See figure from IBM paper below, click to enlarge.)

The approach, say IBM researchers, may enable tackling longer more complicated problems as well as being a general purpose technique.

“Computations on noisy quantum hardware are limited by the competition between decoherence and circuit depth, a measure of the number of sequential operations performed on the processor. Increasing circuit depth can help create more complex quantum states, and in the context of chemistry simulation, this may allow for a better representation of the energy states of the molecules considered. However, increasing circuit depth on a noisy quantum computer typically implies increased errors from decoherence. [W]ith the technique developed in this work, our ability to mitigate the effect of decoherence enables us to access more complex and accurate computations that benefit from increased circuit depth.”

While the new protocol enabled computational accuracies that were otherwise inaccessible to the hardware, the authors caution that it is important to recognize that the improvements are not indefinite and are ultimately limited by the coherence properties of the processor. “As we march towards systems with increasing Quantum Volume, improved coherence, quantum control, and circuit compilation will all contribute to extending the reach to even longer quantum circuits with more qubits,” they write.

D-Wave: It’s All About the Applications

D-Wave remains the only provider of commercially available quantum computers even though they remain research (not production) machines. Its technology – adiabatic annealing – is quite different from universal gate-based models. That said most QC watchers now agree D-wave’s approach is a solid contender for solving classes of optimization problems. Recently, the company unveiled an 18-month roadmap that includes creating a 5000-qubit system (see HPCwire article, D-Wave Previews Next-Gen Platform; Debuts Pegasus Topology; Targets 5000 Qubits).

The emphasis at this week’s D-Wave’s user meeting is on showcasing progress towards real-world applications. D-Wave says “customers have built over 150 early applications on D-Wave computers to date” and lists the following highlight topics from the conference:

• Quantum computing algorithms for optimized planning and scheduling
• Building a hybrid algorithm that will be used as part of a smart mobility solution
• Inferring correlation between future stock returns and their features
• Applications of quantum annealing for blockchain and allocation of television 
commercials
• Quantum annealing–based optimizations of robotic movement in manufacturing
• Optimizing flight gate assignment
• Capacitated vehicle routing
• Quantum chemistry calculations
• Quantitative financial reverse stress testing

“The future of practical quantum computing relies on giving more developers and researchers the access and tools they need to build quantum applications. Expanding Leap globally and bringing customers from around the world together to share their work is critically important to realizing that vision,” said Vern Brownell, CEO of D-Wave in the official announcement. “I’ve never been more confident that true practical quantum applications are within reach in the near future. The range and robustness of early applications from our customers continues to grow, and customers are starting to see early value in using quantum computing to address real-world business problems.”

Northwest Quantum Nexus Sets Aggressive Agenda

Obviously these are early days but the newly-announced Northwest Quantum Nexus is quickly moving to establish directions. At a two-day summit last week announcing NQN, the group issued the following statement:

“In line with the goals of the National Quantum Initiative Act, the Northwest Quantum Nexus accelerates Quantum Information Science (QIS) to develop a quantum economy and workforce in the greater Pacific Northwest region of the United States and Canada. The high concentration of quantum activity in the Northwest makes it one of the top regions globally to address key QIS needs. The goal of the two-day Summit this week is to bring together the region’s experts who can define the region’s potential to drive quantum computing’s future.

Its objectives include:

• Bringing together academia, government, startups, and industry to pursue multi-disciplinary QIS research to deliver scalable quantum computing.
• Pursuing quantum computing via collaborative research and development, targeted quantum algorithms and programming, and the development of quantum materials.
• Capitalizing on public-private partnerships to promote a rapid exchange of knowledge and resources and drive discoveries in quantum technologies.
• Applying research outcomes to application areas and testbeds, including clean energy and sustainability.
• Cultivating the future quantum workforce through programs that range from early to higher education and professional levels, as well as the corresponding network of institutions and outlets offering curriculum and training opportunities.”

Todd Holmdahl, corporate VP of Microsoft Quantum, said “The Northwest Quantum Nexus represents another big step toward the development of scalable, stable quantum computers. The partnership just makes a lot of sense – we’re already one of the top regions in the world for quantum research, and the Nexus will help us leverage that expertise to build a quantum-ready workforce and boost the region and nation’s quantum ecosystem.”

Feature illustration caption: Single qubit trajectories measured at different noise levels (red, green) are used to estimate the error-mitigated trajectory (blue). Source: IBM

Link to IonQ paper: https://arxiv.org/pdf/1903.08181.pdf

Link to IonQ announcement: https://ionq.co/news/march-21-2019-new-benchmarks

Link to IBM paper: https://www.nature.com/articles/s41586-019-1040-7

Link to IBM blog: https://www.ibm.com/blogs/research/2019/03/noise-amplification-quantum-processors

Link to D-Wave announcements: https://www.dwavesys.com/press-releases/d-wave-expands-leap-quantum-cloud-service-and-application-environment-europe-and

Link to X9: https://x9.org