D-Wave executives stirred up some controversy earlier this year when they claimed a smaller version of its Advantage 2 annealing quantum system, armed with 1,200 qubits, had reached “quantum supremacy,” – or “quantum advantage” – that significant but ill-defined time when a quantum system is able to solve a problem in much less time, at a lower cost, or more efficiently than the most powerful classical supercomputer.
D-Wave argued in the journal Science that, using quantum simulations, it computed properties in various magnetic material of different structures, size, and timescales. The Advantage 2 system solved a problem in minutes that company executives said would take the Frontier supercomputer a million years.
The claim quickly drew a range of critics, including the Flatiron Institute and École Polytechnique Fédérale de Lausanne in Switzerland, which said they were able to use classical computing technologies to run the same calculations, a statement that led D-Wave president and chief executive officer Alan Baratz to suggest they were making “overreaching claims.”
D-Wave wasn’t the first make this assertion or face the industry pushback. Google said in 2019 that it reached quantum supremacy with its Sycamore quantum chip, running a computational problem in a few minutes that it said would take the then-fastest supercomputer – Summit, housed at Oak Ridge National Laboratory and powered by IBM and Nvidia silicon – 10,000 years.
Five years later, in December 2024, Google said its new Willow quantum chip ran a benchmarking task in five minutes that would have taken the Frontier exascale system – a supercomputer at Oak Ridge using AMD Epyc CPUs and Instinct MI250X GPU accelerators – 10 septillion (1024) years.
Reaching the quantum advantage stage will be a significant moment. Hrant Gharibyan, co-founder and chief executive officer of quantum software startup BlueQubit, wrote that “with quantum advantage, computing undergoes an evolutionary change that unleashes untapped potential beyond the capabilities of traditional systems,” and made a distinction between quantum supremacy (when a quantum system solves a specific job that the most powerful classical computers can’t) and quantum advantage (scenarios where quantum computers perform better in solving specific problems).
Quantum Advantage In Sight
Members of IBM’s quantum team say they expect the industry will see the first examples of quantum advantage sometime between now and the end of 2026. As noted, claims already have been made and disputed. The IBM Quantum folks believe that will continue, writing this week that “the first claims of quantum advantage are emerging, and over the next few years, we expect researchers and developers to continue presenting compelling hypotheses for quantum advantages. In turn, the broader community will either disprove these hypotheses with cutting-edge techniques — or the advantage holds.”
But what exactly is quantum advantage, and how will we know it when it happens? IBM and quantum computing startup Pasqal released a nine-page white paper this week looks to define quantum advantage, steps for scientifically validating claims, and possible ways to get there.
Armpit Deep In Quantum
IBM, as with other major players like Google, Microsoft, Amazon, and Nokia Bell Labs, is armpit-deep in quantum computing. The company last month detailed a way to address the key challenge of error correction in qubits with a new algorithm that reduces the number of qubits that systems need to correct errors. It also laid out an aggressive roadmap to fault-tolerant, large-scale quantum systems, including the “Loon” quantum processor this year, with more to follow in the coming years.
IBM also is working on “Nighthawk,” a key step toward reaching quantum advantage. Researchers will use it as a platform to address the first instances of quantum advantage. Due out this year, Big Blue will release new iterations over the next four years that will have improved quality and connectivity. By 2028, it will be able to circuits with 15,000 gates and connect up to nine modules l-couplers – which uses cables to connect chips – to reach 1,080 connected qubits.
A new system architecture will result in “Starling,” (below) which will be built by 2028 and become available a year later via a quantum datacenter IBM is building in Poughkeepsie, New York. After that will come “Blue Jay,” a system scheduled for 2033 that will be capable of running 1 billion gates across 2,000 qubits.
Now is the time to tackle the quantum advantage issue, according to Big Blue. Researchers in a blog post – Jay Gambetta, IBM Fellow and vice president of quantum, Borja Peropadre, head of quantum algorithm engineering, Olivia Lanes, global lead for quantum learning, and Ryan Mandelbaum, editor in chief of IBM Quantum – note that quantum computing already can run computations that the beset classical algorithms can and that experiments on the systems are competitive with the best classical approximation methods.
“At the same time, computing researchers are testing advantage claims with innovative new classical approaches,” they wrote.
According to the white paper, for something to reach quantum advantage it has to meet two criteria: the correctness of the system’s output must be able to be rigorously validated and can show that it done with better efficiency, cost-effectiveness, or accuracy than what classical computing can do alone.
“We don’t expect quantum advantages to be achieved by quantum computers acting alone,” the researchers wrote. “Instead, they will emerge from use cases where we leverage quantum computers to augment a classical workflow. So, quantum advantage really means that ‘quantum plus classical’ can outperform classical alone.”
The ideal benchmark is “unconditional quantum separation,” a proven difference in the algorithmic performance between quantum and classical computers. Some have identified potential examples of such gaps, but most results don’t show the significant performance advantage that quantum systems promise.
IBM expects the first claims of quantum advantage will come from efforts in sampling problems, variational programs, and calculating the expectation values of observables. The challenge now will be to “rigorously confirm” when an advantage has occurred, the researchers wrote. Each part of the computation will have to be verified on their own merit through error detection and mitigation.
Those making a claim will have to hypothesize and validate, while others on the outside will try to support or disprove the claim.
“This back-and-forth will continue until we reach a consensus,” the researchers wrote. “We also believe that it positions variational problems and calculating expectation values as likely delivering the first proven advantages, given our ability to validate these kinds of problems. That leads to a critical point: quantum advantage won’t be a single moment in time. Rather, we’ll see a number of hypotheses tested until eventually the community determines that quantum advantages have been realized.”
More To Be Done
After that, the work continues.
“By the end of next year, we predict that the community will coalesce around an agreement over the first demonstrations of quantum advantages,” they wrote. “From that point forward, we will continue searching for new algorithms that extract further value from quantum computers.”
Research groups that are using quantum systems are defining possible paths to quantum advantage by running algorithms through the systems to find applications that classical computers can’t address by themselves. IBM noted that startup Kipu Quantum in May announced a runtime quantum advantage, saying its algorithm fan faster than classical solvers for higher-order unconstrained binary (HUBO) optimization problems.
In addition, Q-CTRL last month claimed a study done with Network Rail, a UK railway infrastructure company, and the UK’s Department for Transport showed that quantum software could improve the performance of quantum hardware to the point that it will reach quantum advantage in transport logistics by 2028.
