What must happen for quantum computing to reach the general public?



If you extend the quantum computing timeline to the IBM computer timeline, we’re somewhere between the vacuum tube machines of the 1940s and the models built on transistors, ICs, and silicon of the 1960s. And we are much closer to the first.

“In a sense, we didn’t even dwell on the technology,” said Celia Merzbacher, executive director of the Quantum Economic Development Consortium. “We’re not all on the same page when it comes to what the transistor will be – let alone how the integrated circuit is going to work – but we benefit a lot from these experiences from the semiconductor version of it. ‘computer science .”

In his talk on the state of advancement of quantum computing last week at Data Center World in Orlando, Merzbacher described a technology that is still in its infancy.

Advances in the field are closely linked to the amount of qubits (basic units of quantum information) that engineers manage to put to work together. A thousand logical qubits is considered the minimum to do anything meaningful, but you need a million physical qubits to have 1000 logical. This is because physical qubits are sensitive to vibration, and you need a lot of it “in order to correct noise and errors in qubits today,” she explained.

“I think when we take certain steps, things can go pretty quickly through the scaling and come up with this one million qubit system where we can do something useful.”

Cooling quantum computers: “Any temperature is really the enemy”

The quatum computers that tend to make the headlines these days – those built by IBM, Google, and Rigetti – are based on superconducting qubits and require extremely low temperatures to operate: around -460F, or near absolute zero. Needless to say, cooling these machines is a big expense, especially given their large size.

As an example, Merzbacher pointed to the 10-by-6-foot cryogenic refrigeration system that IBM is developing to house its 1,000-qubit quantum machine. “They’re going to keep that big volume at absolute zero, or at millikelvin temperatures,” she said.

Although little is known about the power required to cool IBM’s quantum machines, there is some data on the cooling of Google’s quantum computers. Alan Ho, who until last month led product management at Google Quantum AI, joined Merzbacher’s talk via a recording and said it takes 25 kW to cool one of their quantum computers.

He added that the custom electronics running the processor only need 1kW peak, which means that despite the high cooling cost, their quantum computers are much more energy efficient than traditional computers given their speed. He said this was demonstrated in 2019 in a comparative study, in which a Google Sycamore quantum machine and the Oak Ridge National Lab summit (currently the second fastest supercomputer in the world, according to Top500) were running the same complex calculation.

“The result has been about a billion times acceleration on the Google Sycamore processor compared to the Summit supercomputer,” he said. “When you think about it from an energy point of view, a Summit supercomputer takes control of around 14 MW in total, while the Google processor takes around 25 kW, which means that from a computational point of view it is about a trillion times more energy efficient than the Google quantum Sycamore processor. on top of Oak Ridge. “

But Merzbacher said several companies are working on designs that don’t require such extreme cooling. The startup PsiQuantum, for example, is a developing quantum computer based on photons, while Honeywell and another startup, IonQ, are working on “trapped ion” designs. In addition, the French startup Pasqal is developing a quantum computer using an “atom neutral” design.

Each of the technologies has its pros and cons, she said. “Some of them, like trapped ions and neutral atoms, can be at room temperature. Although they all do better at low temperatures because they are all very sensitive to noise, including thermal noise. temperature is truly the enemy of a quantum system. “

Promising first applications for quantum computers

Merzbacher pointed out that quantum computers will not replace conventional computers, but will be used primarily to run workloads that are impossible, or very difficult, to run on conventional computers.

“We don’t really know what the killing app will be or what area they’ll be [quatum computers] have such an advantage that they’re going to be very disruptive, “she said.” Probably, even if we thought we knew, we would be wrong. “

Although the exact workloads remain unknown, computer scientists have ideas on where quantum computers will be of value. One promising area, she said, is the modeling of biological processes. For example, scientists could use quantum computers to model the energy states of chlorophyll to better understand how photosynthesis efficiently converts sunlight into energy.

“We don’t really have a clue how nature does this,” Merzbacher said. “In order to be able to model systems like this, you need a very different type of computer. It quickly exceeds what a conventional computer can do.”

Other areas include studying things like corrosion, to help industries design materials with desired qualities, as well as optimizing systems, which will be useful for everything from helping Amazon and FedEx to optimize the routes of their massive fleets to help financial institutions optimize investment portfolios.

“Machine learning is another area – perhaps a little more distant – where quantum computers can provide something that current systems don’t,” she said.

Unfortunately, quantum computers are also expected to be good at breaking down current encryption methods.

“Shor’s algorithm is a prime number factorization algorithm, and it is ultimately believed that quantum computers will be able to perform this algorithm and in fact break the prime number based encryption standards that are widely used today. “she said.

While quantum computers that will be able to break current encryption standards are expected to be 10 to 15 years away, it will take another 10 or more years to migrate to a new, more secure encryption standard, Merzbacher said, suggesting that it is. probably a good idea to start figuring out what that standard will be now.


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