Honeywell Announces "World's Most Advanced Quantum Computer"

This week Honeywell announced that they will be releasing the “world's most advanced quantum computer” within the next few months. We in the quantum computing field love to hear announcements like this one, as any significant breakthrough ultimately benefits all our work in this budding industry. But whether you are a quantum computing engineer, or a casual quantum enthusiast, you might have the same question. What does it mean to be the worlds most advanced quantum computer?

To tackle this question, let's start by talking about how Honeywell is building its quantum computer. Honeywell employs a promising quantum computing architecture that leverages “trapped-ion qubits”. As of today there are many different ways companies are exploring to build quantum computers. Many, including Google an IBM, are using superconducting. PsiQuantum is making strides with photonics. Microsoft is taking perhaps the most ambitious approach, banking on something called topological quantum computing, which is based on -what was until recently - a theoretical particle called the Majorana particle. If they are successful, topological quantum computers could be much easier to scale in part due to their less-error-prone qubits.

Another approach that shows promise thanks to its lower error rates are ion-trap quantum computers. Trapped-ion quantum computers promise to harness qubits that can hold their state longer, produce less error-prone outputs, and can even operate at room temperature - addressing a challenge faced by other architectures that require conditions close to absolute zero to function. The reasons that trapped-ions have not become the standard, is that they are - in theory - harder to scale than something like superconducting systems. With this announcement however, many are hopeful that Honeywell may have found novel ways to scale up their ion-trapping system.

But Honeywell’s announcement shows promise not simply because of its demonstrated scalability. To really dive in to their claim, we have to talk about quantum volume. So what is quantum volume? It is the measure proposed by IBM that goes beyond just the number of qubits that a quantum computer wields. It became clear that we needed a new measure of quality, not just quantity, because we have begun to see significant variation in things like error rates and connectivity when we compare qubits from one machine to another. These measures, in addition to qubit count, are what allow us to perform longer, more complex, and more accurate computations. When we analyze these together, we get quantum volume - a way to compare qubits across companies and architectures.

Now we can return to the original question of what it means to be the worlds “most advanced quantum computer”. When Honeywell made this claim, they were talking about the quantum volume that they have reportedly been able to achieve using their trapped-ion system. Honeywell claims that when it releases its quantum computer in the summer later this year, it will have a quantum volume of at least 64 - or twice that of the next available alternative (which is a reference to IBM Q’s 28 qubit superconducting quantum computer). Now, since IBM is the only other company besides Honeywell that publishes their quantum volume measure, this is a somewhat controversial statement. Not surprisingly IBM responded to Honeywell's announcement first by applauding their advancement, and adding:

“IBM has reached a quantum volume of 32 on a 28-qubit superconducting system, which was announced in January of this year — and the company expects to continue to double quantum volume every year. The scaling and doubling of quantum volume each year we refer to as Gambetta’s Law. Honeywell’s paper shows exciting new progress in programmable trapped-ion quantum systems.”

So yes, even IBM agrees this is an exciting step forward in the quantum computing hardware world. But a lot can happen between now and the summertime. IBM could very well come out with a stronger contender before then. We are also hoping to see advancements from others in the space including Rigetti, PsiQuantum, and IonQ in the near future. Personally, I was thrilled to hear Honeywell’s announcement, and I am perhaps just as excited about the competition this will likely inspire, which will push for competitors to accelerate their work.

With bigger and higher-quality quantum computers, comes the increased potential to build real world applications that will run laps around their classical counterparts. Today, we sit squarely in the NISQ era. Our most important goal right now is developing qubits of high enough quality to give us reliable, consistent, and accurate calculations. Honeywell’s announcement is an exciting one in this context, bringing us one step closer to our bright quantum computing future.