Honeywell doesn’t spring to mind when thinking of quantum computing pioneers, but a decade ago the high-tech conglomerate better known for its control systems waded deliberately into the then calmer quantum computing (QC) waters. Fast forward to March when Honeywell announced plans to introduce an ion trap-based quantum computer whose ‘performance’ would rival any other quantum computer now available.
The forthcoming Honeywell system is expected in mid 2020 and already being trialed by a few beta users including JPMorgan Chase. The new system will boast a Quantum Volume (QV) benchmark of 64 according to Honeywell, the highest QV yet reported. QV, of course, is a blended metric developed by IBM. It’s intended to represent a machine’s overall utility by taking into account things like qubit count, coherence times, qubit connectivity, and error rates. IBM’s top performing system currently has a QV 32 rating. IBM says it plans to double its QV rating yearly. Honeywell, meanwhile, says it will raise its QV 10X every year for the next five years eventually getting to a QV of 640,000.
Notably, Honeywell’s new system will have just six qubits. IBM’s ‘biggest’ system has 53 qubits but its top performer, interestingly, is a 28-qubit system (named Raleigh) with a QV 32 rating. QV, contends IBM, is a better yardstick for gauging performance and progress towards achieving quantum advantage – the crossover where QC performance for a particular application is sufficiently better than on a classical HPC system to warrant switching.
“We agree with IBM that quantum volume is as good a metric as exists today. What had been happening was people were using physical qubits as a proxy [for performance]. That’s a terrible proxy. That does not even remotely tell you what you can actually go do with those physical cubits,” said Tony Uttley, president, quantum solutions, Honeywell.
In fact, many observers agree. The nascent quantum computing community is striving to develop meaningful, widely-agreed upon benchmarks (SeeHPCwire articles on IBM efforts and DoE efforts). How influential IBM’s QV will become is unclear. But this getting ahead of the story. Uttley recently briefed HPCwire on Honeywell’s quantum initiative which began with recognizing the potential importance of quantum computing and its own substantial pool of requisite resources.
“The underlying technologies that you need to build any quantum computer are things that we have been doing for decades and are parts of our business. That includes vacuum systems, or in our case, ultra-high vacuum systems. It includes cryogenics, magnetic systems, vibrational stability, lasers and photonics, and precision control systems. Those were the places where we had a deep domain expertise and decades of IP,” said Uttley.
“The reason we chose trapped ion technology is that it has the advantage of starting with a perfect quantum bit.”
Research into using ion trap technology for quantum computing has simmered for years. Long coherence times and higher gate fidelity are considered its strengths while slower gate times and difficulty scaling up the number of qubits have been thought challenging. The latter, of course, is challenging for all qubit technologies. Also deep cold is still required. The Honeywell trap is cooled to 12.6 K via a cold finger attached to a liquid He flow cryostat.
Honeywell published a paper (Demonstration of the QCCD trapped-ion quantum computer architecture) in March describing its approach.
Broadly (and with apologies for garbling), ion trap uses ions as qubits. These ion qubits are held in in line by magnetic resonance forces. It’s possible to interact with the qubits using photonics (e.g. lasers) and, for example, to entangle neighboring qubits to execute a two-qubit gate. There is an NSF program (STAQ) exploring ion technology for quantum computing and IonQ is a start-up also developing an ion trap machine and also touting superior performance.
Here’s a brief description taken from the Honeywell paper:
“The system employs 171Yb+ ions for qubits and 138Ba+ ions for sympathetic cooling and is built around a Honeywell cryogenic surface trap capable of arbitrary ion rearrangement and parallel gate operations across multiple zones. As a minimal demonstration, we use two spatially-separated interaction zones in parallel to execute arbitrary four-qubit quantum circuits. The architecture is benchmarked at both the component level and at the holistic level through a variety of means. Individual components including state preparation and measurement, single-qubit gates, and two-qubit gates are characterized with randomized benchmarking. Holistic tests include parallelized randomized benchmarking showing that the cross-talk between different gate regions is negligible, a teleported CNOT gate utilizing mid-circuit measurement, and a quantum volume measurement of 24.”
Think of QV as a measure of effective qubits in which the final QV value is 2n where n is the number of effective cubits.
“So far every qubit we’ve put in our system is an effective qubit. Meaning it took only four qubits to get to a QV16 and it’s only going to take six qubits to get to 64. Which is why we also felt very confident saying, we’re going to be able to increase our quantum volume by at least an order of magnitude. So at least 10x every year for the next five years,” says Uttley.
“Our first architecture is a linear architecture. There is a runway and you have different planes lined up on the runway, and you can take and move them around, such that any one plane on the runway can be next to any other plane on the runway. And we have zones up on the trap itself. So we can do simultaneous gating. We can do simultaneous quantum operations on multiple qubits all at the same time. Being able to do that in real time was a challenge. But because we were able to do that work first, that allows us to now scale much more rapidly,” he said.
Uttley said the system as designed would scale easily because the heavy lifting required to develop and implement controls was finished. He compared it to an auditorium in which all the infrastructure was present and adding qubits was like adding seats.
“We have six seats – six qubits in there – are be able to do all the operations to get to a quantum volume 64, but then you can just add in four more qubits to get to n equals 10 which gets it to a QV of over 1000. So why are we confident about that? Because it’s literally the exact same system. We don’t have to go build a different one. We’ve put all of the infrastructure around it, all the systems to make it work, and we’re just filling a few seats at a time. But that auditorium is a big auditorium and so using the same system that gets us to a quantum volume of 64 is the system that will allow us to get to a combine of 640,000,”he said.There is of course the straightforward question of how many qubits are needed to solve practical problems and estimates vary widely on that topic. A QV score of 640,000 is only impressive if it allows you to do something worthwhile.
Uttley describes three eras for quantum computing. We’re now in the emergent era trying to create a base. Next will be the “classically impractical” era, which roughly corresponds to when quantum computers will be able to tackle problems that basically take too long or cost too much ($ or energy) to be done on classical computers. The third era, “classically impossible,” will be when quantum computers are able to tackle problems that simply couldn’t be done on classical resources.
Citing applications in machine learning, chemistry, and optimization, Uttley said he believes 3-to-5 years is a reasonable window for achieving quantum advantage. He is also optimistic about the developing software ecosystem and indeed Honeywell has invested in two early tool-makers there, Cambridge Quantum Computing and Zapata Computing.
“One of the things we’ve talked about that hasn’t gotten of picked up as much as I would have thought is the capability we have called mid-circuit measurement. It’s a circuit measurement in the middle of a quantum computation. We can pause [execution], interact with a single qubit, interrogate it and say, “What are you right now? Are you a zero? Are you a one?” Then based upon the answer, we can do something different with the rest of the computation. In real time. It is the quantum computing equivalent of putting an “if” statement into the quantum algorithm. It opens up such a vast area of potential within quantum algorithm development.”
Like most quantum computer makers Honeywell will roll out its services via portals.
“Access tends to take three shapes. First are companies that have their own quantum algorithm development capabilities and there aren’t a lot of them. JPMorgan Chase is great example. They have experts who know how to program quantum computers. They can have a direct access to the cloud API that comes in and run the jobs and get results back,” said Uttley. “The second path is through partners like Cambridge Quantum Computing. They have enterprise software capabilities to abstract some of the quantum computing language as well as people who can take the business problem and translate it into a quantum circuit.” The third path will be through Microsoft Azure’s quantum solutions portal.
Time will tell how well Honeywell’s bet on ion trap technology pays off. Semiconductor-based superconducting (e.g. IBM, Google, Rigetti) is the other dominant approach. Silicon spin (quantum dots, Intel) and Microsoft’s pursuit of topological qubits are others. No one yet knows how the jostling will settle out. Many quantum observers, Uttley included, say it’s best to think of quantum computers as special purpose devices, not unlike GPUs, that will handle specific jobs. Moreover, the differing qubit technologies are likely to have distinct strengths within specific application areas. There won’t be a winner take all.
Technology questions aside, Honeywell believes quantum computing will be a game changer. Uttley says the company wants to be its own best customer, focused on applications spanning aerospace, chemicals, and surfactant businesses.
“I think, in total, one of the reasons why Honeywell made this decision 10 years ago and has continued at it through to where we are today is fundamentally our belief that any multi industrial is going to be profoundly impacted by quantum computing,” said Uttley. “You are either going to have to figure out how to adjust to that when it happens. Or in our case, not just embrace it, but literally help shape how it evolves across the different industries in which we operate. We expect to be leaders in quantum computing going forward.”