Rob Hays, CEO

Today, researchers at Atom Computing released a pre-print publication on arXiv , demonstrating the ability to perform mid-circuit measurement on arbitrary qubits without disrupting others in an atomic array. The team applied mid-circuit measurement to detect the loss of qubits from the array (a well-known anticipated error), and successfully replaced the lost qubits from a nearby reservoir.

Path to Fault Tolerance

At Atom Computing, we believe the true potential of quantum computing will be achieved when devices are capable of fault-tolerant computation.  Our company’s focus is on leading that race to unlock the enormous potential of quantum computing applications for industrial and scientific uses. 

Dr. John Preskill, famed theoretical physics professor at California Institute of Technology, who coined the phrase Noisy Intermediate Scale Quantum (NISQ) to describe the current stage of quantum computing, said it best in 2018: “We must not lose sight of the essential longer-term goal: hastening the onset of the fault tolerant era.”

It will likely require hundreds of thousands or millions of physical qubits to achieve fault tolerant systems that can operate continuously and deliver accurate results, overcoming any errors that may occur during computation just as classical computing systems do.  Mid-circuit measurement is one of several key building blocks required to achieve fault tolerant systems:

• Large numbers of physical qubits
• Long coherence times
• High gate fidelities
• Mid-circuit measurement
• Detection and correction of errors in real time
• Algorithm and controls to create logical qubits

Mid-circuit measurement has been demonstrated on superconducting and trapped-ion quantum technologies.  Atom Computing, however, is the first company to do so on a commercial atomic array system.  Recent achievements in the neutral atom research community have shown that atomic arrays are emerging from their “dark horse” status to a preferred architecture with intriguing potential.

Importance of Mid-Circuit Measurement

In quantum computing, circuits act as instructions that tell a quantum computer how to perform a calculation.  Circuits define how the programmer intends for the qubits to interact, which gates they need to complete, and in what order they need to be performed.

Mid-circuit measurement involves probing the quantum state of certain qubits, known as ancillas, without disrupting nearby data qubits that perform calculations.  The ability to measure or read out specific qubits during computation without disrupting the rest is essential for quantum developers.  It enables them to glimpse inside a calculation and use conditional branching to determine which action to take based on results of the measurement, similar to IF/THEN statements used in classical computing. With this capability errors can be detected, identified, and corrected in real time. 

Dr. Ben Bloom, Atom Computing Founder and Chief Technology Officer, called this demonstration an important step for the company’s technology, which uses lasers to hold neutral atom qubits in a two-dimensional array to perform computations.

“This is further proof that atomic array quantum computers are rapidly gaining ground in the race to build large-scale, fault-tolerant quantum computers,” Bloom said. “Mid-circuit measurement enables us to understand what is happening during a computation and make decisions based on the information we are seeing,”

Doing this is tricky. Qubits, whether they are in an atomic array, ion trap, or on a chip, are situated microscopically close. Qubits are finicky, fragile, and sensitive.  A stray photon from a laser or a stray electric field can cause the wrong qubit to decohere and lose its quantum state. 

The Atom Computing team exhibited a technique to “hide” data qubits and shield them from the laser used to measure ancillas without losing any of the quantum information stored in the data qubits. They also showed a competitive SPAM fidelity, a metric that states how well a qubit can be read out. This work demonstrates an important pathway to continuous circuit processing.

What’s Next

Atom Computing is building quantum computers from arrays of neutral atoms because of the potential to significantly scale qubit numbers with each generation.  We previously demonstrated record coherence times on our 100-qubit prototype system and are now working on larger scale production systems to offer as a commercial cloud service.  Our demonstration of mid-circuit measurement, error detection, and correction was performed on these next-generation systems.

Our journey toward fault tolerance continues. We are working to achieve all the necessary “ingredients” listed above on our current systems and on future machines with the Defense Advanced Research Projects Agency.  DARPA selected Atom Computing to explore how atomic arrays of neutral atoms can accelerate the path to fault-tolerant quantum computing.

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Dr. Jonathan King, Chief Scientist and Co-Founder

I am pleased to welcome two renowned researchers in the field of quantum information science to Atom Computing as independent scientific advisors. 

Dr. Bert de Jong, Senior Scientist and Deputy Director of the Quantum Systems Accelerator at Lawrence Berkeley National Laboratory, and Dr. Eliot Kapit, Associate Professor of Physics and Director of Quantum Engineering at Colorado School of Mines, join our long-time advisor Dr. Jun Ye, Professor of Physics at University of Colorado-Boulder and Fellow at JILA and the National Institutes of Standards and Technology.  Together, these scientists and academic leaders will help us advance the state of the art in quantum computing by providing deep technical expertise and guidance to our team. 

Since its inception in 2018, Atom Computing has been building quantum computers from atomic arrays of optically trapped neutral atoms with the goal of delivering large-scale fault-tolerant quantum computing for a range of use cases and applications.  Building high-quality quantum computers is hard work that requires tight collaboration across our team of theoretical and experimental physicists and engineers of multiple disciplines. 

We also frequently consult with researchers from other organizations to solve difficult technical challenges.   In addition to our scientific advisors, we also have active collaborations with other experts from Sandia National Laboratories, DARPA, University of Washington, University of Colorado-Boulder, and others to support R&D of technologies required for our future roadmap.

We are at the point where we are focusing not only on developing our hardware, but also what users can do with it to solve commercial problems at scale.  Bert and Eliot are experts in quantum computing use cases and algorithms.  Their expertise will help our quantum applications team and customers learn how to get the most value out of our hardware platforms.

Bert leads Lawrence Berkeley National Laboratory’s Computational Sciences department and its Applied Computing for Scientific Discovery Group. His group’s research encompasses exascale computing, quantum computing and AI for scientific discovery.  (View his bio.) 

When asked about the role, Bert stated, "Atom Computing's path to universal quantum computing with atom arrays is exciting, and I am honored to be a scientific advisor providing critical input and guidance into their software and algorithm strategies.”

Eliot’s research at Colorado School of Mines focuses on quantum information science, particularly routes to achieve practical and scalable quantum advantage in noisy, near-term hardware.  (View his bio). 

Here is what Eliot said about his new role: “I'm excited to have joined the scientific advisory board at Atom Computing. Neutral atom quantum computing has progressed shockingly quickly in just the past few years - and I say this as someone who's been working on superconducting qubits for the past decade, which certainly haven't been standing still.  I think Atom, in particular, has both a compelling roadmap toward large scale quantum computers, and a very capable team to make it happen.”

I am looking forward to future collaborations with Bert, Eliot, and Jun to drive large-scale quantum computing with applications that change the world.

In recent months, researchers from different institutions won major physics awards for advancing optical tweezer arrays and their use in quantum information sciences.

These announcements drew broader attention to optical tweezer arrays, even in the physics community.  At Atom Computing, however, they are always top-of-mind – optical tweezers are critical to our atomic array quantum computing technology. 

What are optical tweezer arrays and how and why do we use them in our quantum computers? Dr. Remy Notermans, who helped develop the optical tweezer array for Phoenix, our prototype system, answers these questions and more.

What are optical tweezer arrays?
A single optical tweezer is a beam of light used to capture atoms, molecules, cells, or nanoparticles, hold them in place or move them as needed. 

This is possible because light can attract or repulse a particle depending on the color (wavelength) of the light and the absorption properties (electronic energy level structure) of the particle.  By choosing the right wavelength, a particle will be drawn or attracted to the region with the highest intensity of light, trapped in what is known as a potential well (the energy landscape in which an atom wants to go to the lowest point.)

An optical tweezer is created when a laser beam is focused through a microscope objective lens. As the laser beam gets focused it forms into a "tweezer" capable of holding miniscule objects and manipulating them in its focal point. Think of the tractor beam from Star Trek.

To create an optical tweezer array, the laser beam is manipulated before it is focused through a microscope object lens to create a custom-made array of optical tweezers that can be tailored to specific needs – topology, dimensions, and orientation.

Are optical tweezer arrays a new technology?
Optical tweezers have been used by researchers in the fields of medicine, genetics, and chemistry for decades. In fact, Arthur Ashkin, “the father of optical tweezers,” was awarded the Nobel Prize in Physics in 2018. Ashkin’s work dates to 1970 when he first detected optical scattering and the effect of different levels of force on particles the size of microns.  He and some of his colleagues later observed a focused beam of light holding tiny particles in place – or optical tweezers.

More recent scientific work has expanded to actual arrays of optical tweezers, allowing for studying many particles simultaneously, biophysics research, and of course quantum information processing.

How does Atom Computing use optical tweezer arrays? What are the benefits?
Optical tweezers are critical to our atomic array quantum computing technology, which uses neutral atoms as qubits.  We reflect a laser beam off a spatial light modulator to create an array of many optical tweezers that each “trap” an individual qubit.  For example, Phoenix, our 100-qubit prototype quantum computer, has more than 200 optical tweezers created from a single laser. Each tweezer can be individually calibrated and optimized to ensure precise control. 

Optical tweezer arrays enable us to fit many qubits in a very small amount of space, which means that scaling the number of qubits by orders of magnitude does not significantly change the size of our quantum processing unit.  By integrating clever optical designs, we foresee a sustainable path toward atomic arrays that are large enough for fault-tolerant quantum computing.

In fact, optical tweezers inspired the Atom Computing logo.  If you turn our “A” logo upside down, it is a visual representation of an optical tweezer holding an atom in a potential well.

Are optical tweezer arrays used for other purposes?
Yes, optical tweezer arrays have been used extensively by researchers in other scientific fields. They have been used by scientists to trap living cells, viruses, bacteria, molecules, and even DNA strands so they can be studied.

Has the work of the New Horizons Physics Prize winners influenced Atom Computing’s approach? If so, how? 
We understand this is a fundamental part of the academic-industrial ecosystem, which is why Atom Computing is involved with many partnerships and funds academic research efforts that potentially help us propel our technology forward.  Combined with the knowledge and experience of our world-class engineering teams, we take these breakthroughs to the next level in terms of scalability, robustness, and systems integration.