This new startup is building a record-breaking 256-qubit quantum computer
In 2019, Google announced that its 53-qubit engine had achieved quantum supremacy — doing a task that could not be managed by a convention computer — but IBM challenged the claim. In the same year, IBM launched the 53-bit quantum computer. In 2020, IonQ opens up a 32-qubit system that the company calls “the world’s most powerful quantum computer.” And this week IBM unveiled the new 127-qubit quantum processor, described in a press release as a “little design miracle.” “The big news, from my perspective, is that it will work,” said Jay Gambetta, vice president of quantum computing at IBM.
Now QuEra claims to be making a device with more qubits than any of its rivals.
The ultimate goal of quantum computing, of course, is not to play Tetris but to surpass classical computers in solving problems of practical interest. Enthusiasts consider that if these computers become powerful, perhaps in a decade or two, they could bring transformative effects in fields such as medicine and finance, neuroscience and AI. Quantum machines are likely to require thousands of qubits to handle such complex problems.
The number of qubits, however, isn’t the only factor that matters.
QuEra also announced the improved programming of its device, where each qubit is a single, ultra-cold atom. These atoms are precisely arranged in a series of lasers (physicists call them optical tweezers). The setting of qubits allows the machine to be programmed, adapted to the problem being investigated, and even reconfigured in real time in the calculation process.
“Different problems will require the atoms to be placed in different configurations,” said Alex Keesling, QuEra’s CEO and co-inventor of the technology. “One of the unique things about our machine is that every time we run it, a few times a second, we can completely change the geometry and the connection of the qubits.”
The advantage of the atom
The QuEra engine was built from a blueprint and technologies refined over many years, led by Mikhail Lukin and Markus Greiner at Harvard and Vladan Vuletić and Dirk Englund at MIT (all on QuEra’s founding team). In 2017, an earlier model of the device from the Harvard group was used only 51 cubits; in 2020, they will showcase the 256-qubit machine. Within two years the QuEra team hopes to reach 1,000 qubits, and then, with no platform changes, they hope to continue to scale the system beyond hundreds of thousands of qubits.
It is the unique QuEra platform — the physical way the system is assembled, and the way in which information is encoded and processed — that will allow such leaps in scale.
While Google and IBM’s quantum computing systems use superconducting qubits, and IonQ uses trapped ions, QuEra’s platform uses arrays of neutral atoms that produce qubits with impressive coherence (i.e., high levels of ” quantumness “). The machine uses laser pulses to interact with the atoms, turning them into an energy state — a “Rydberg state,” described in 1888 by Swedish physicist Johannes Rydberg — where they can of quantum logic in a robust manner with high fidelity. it Rydberg’s approach on quantum computing worked for decades, but advances in technology — for example, in lasers and photonics — were necessary for it to operate reliably.
When computer scientist Umesh Vazirani, director of the Berkeley Quantum Computation Center, first learned about Lukin’s research on these lines, he felt “unreasonable excitement” —it seemed a strange way, even though Vazirani asks if his intuition has anything to do with reality. “We have a variety of well-developed pathways, such as superconductors and ion traps, that work for a long time,” he said. “Don’t we have to think about different schemes?” He checked in with John Preskill, a physicist at the California Institute of Technology and the director of the Institute for Quantum Information and Matter, who assured Vazirani that his excitement was justified.
Preskill finds Rydberg platforms (not just QuEra’s) interesting because they create highly interactive qubits that are highly interconnected— “and there’s quantum magic,” he says. “I’m very excited about the potential in the short span of time to discover the unexpected.”
In addition to imitation and understanding quantum materials and dynamics, QuEra works on quantum algorithms for solving computational optimization problems that is NP-complete (which is, very difficult). “These are the first examples of useful quantum advantage involving scientific applications,” Lukin said.