Two (electrons) is Better than One

Kortny Rolston-Duce, Director of Marketing Communications

February 7th is National Periodic Table Day, a time to celebrate this ubiquitous chart.  

While versions of element tables sorted by various properties or masses have existed throughout the centuries, the modern Periodic Table of the Elements  emerged in the 1860s. It is arranged by increasing atomic number, which represents the number of protons in the nucleus of each atom.  

Here at Atom Computing, we are partial to alkaline earth metals, members of group two on the periodic table.  We use atoms of alkaline earth metals as qubits in our atomic array quantum computing hardware technology.

What are alkaline earth metals? What makes them well suited for our atomic array quantum computing technology? Dr. Mickey McDonald, Principal Quantum Engineer and Technical Lead, explains: 

What are alkaline earth metals?

Alkaline earth metals are all the atoms that live in the second column of the periodic table. The column number corresponds to the number of electrons that are contained in the atom’s outermost shell. Alkaline earth metals have two. There are also a few atoms in the periodic table which don’t live in the second column but still share a very similar electronic structure—the so-called “alkaline earth-like metals.”

Why does Atom Computing use alkaline earth metal atoms as qubits? 

There are two primary reasons.  The first reason is that alkaline earth metal atoms captured in optical tweezers will oscillate at very high frequencies with high stability.  For decades, researchers at places like the National Institute of Standards and Technologies (NIST) have pioneered the use of these long-lived “metastable” states to create extremely fast clocks that harness quantum effects to measure time to incredible precision.  We leverage the techniques used for timekeeping and apply them to our quantum computers.

The second reason is the structure of an alkaline earth atom guarantees that certain pairs of energy levels called “nuclear spin states” will be insensitive to external perturbations. In atoms with only a single outer-shell electron, that electron’s “spin” can couple strongly to external magnetic fields and the various angular momenta of the rest of the atom’s structure.  That coupling leads to drifts that can interfere with the qubit’s coherence. The spins of the two electrons present in alkaline earth metals “cancel out” in a way that makes certain energy levels much less sensitive to ambient fields.

What are the benefits of nuclear spin qubits?

Structure-wise, the electron outer-shell electron in alkaline earths is the big difference and what allows us to create these very environmentally insensitive nuclear spin state qubits.  Once we encode quantum information in the nuclear spin states, the information remains coherent for tens of seconds because the nuclear spin states are so well-protected from the environment. 

Another benefit is a little more esoteric, but very exciting to me as an engineer and a physicist. We use a technique called “laser cooling” to prepare samples of atoms at temperatures only a few millionths of a degree above absolute zero, which involves shining carefully tuned lasers at atoms and extracting a bit of energy from them one photon at a time. Alkaline earth atoms have a structure complex enough to allow several different colors of laser to be used for this cooling. We combine those different colors to rapidly produce samples of atoms at microkelvin temperatures, whereas other species of atoms require cooling schemes to be more complicated and take longer to reach such low temperatures.

What else makes alkaline earth metal atoms attractive for quantum computing?

We can use the atomic level structure kind of like a Swiss army knife.  Certain states are good for cooling, others are good for storing quantum information, others are good for driving entangling operations.  These unique characteristics make neutral atom qubits and Atom Computing possible!

What Developers Need to Know about our Atomic Array Quantum Computing Technology

Justin Ging, Chief Product Officer

If you are a developer working in the quantum computing space, you are familiar with or have run a circuit on a superconducting or trapped ion quantum computer. 

These two technologies were the early pioneers of the quantum hardware landscape and small versions of each have been available commercially for years.  A major challenge with these approaches is how to scale them to thousands or millions of qubits with error correction.

More recently, an alternative quantum computing technology with the potential to scale much quicker and easier has emerged - systems based on atomic arrays of neutral atoms.   These systems have inherent advantages, which have led to multiple teams developing them.  

But just as there is more than one way to cook an egg, there are different approaches to building quantum computers from atomic arrays.

At Atom Computing, we are pioneering an approach to deliver highly scalable gate-based quantum computing systems with large numbers of qubits, long coherence times, and high fidelities. 

Here are some key advantages of our atomic array quantum computing technology:

  1. Long coherence times.  Most quantum hardware companies measure coherence in units of milliseconds.  We measure it in seconds. The Atom team recently set a record for the longest coherence time in a quantum computer with Phoenix, our first-generation 100-qubit system. Phoenix demonstrated qubit coherence times of 21 seconds.  The longer qubits maintain their quantum state, the better.  Developers can run deeper circuits for more complex calculations and there is more time to detect and correct errors during computation.  How do we create such long-lived qubits? Weuse alkaline earth atoms for our qubits. These atoms do not have an electrical charge, thus they are “neutral.”  Each atom is identical, which helps with quality control, and are highly immune to environmental noise.
  2. Flexible, gate-based architecture.  Atom Computing is focused on developing a flexible and agile platform for quantum computing by supporting a universal quantum gate-set that can be programmed using standard industry quantum development platforms.  This gate-based approach allows developers to create a wide range of quantum algorithms for many use cases.  Our qubit connectivity uses Rydberg interactions where the atoms are excited to a highly energized level using laser pulses causing their electrons to orbit the nucleus at a greater distance than their ground state to interact with nearby atoms.
  3. Designed to scale.  Neutral atoms can be tightly packed into a computational array of qubits, making the quantum processor core just fractions of a cubic millimeter.  Lasers hold the atomic qubits in position in this tight array and manipulate their quantum states wirelessly with pulses of light to perform computations. This arrangement of individually trapped atoms, spaced only microns apart, allows for massive scalability, as it is possible to expand the qubit array size without substantially changing the overall footprint of the system.  For example, at a 4-micron pitch between each atom and arranged in a 3D array, a million qubits could fit in less than 1/10th of a cubic millimeter volume.

Developers looking for gate-based quantum computers with large numbers of qubits with long coherence times, should be looking to partner with Atom Computing.  We are working with private beta partners to facilitate their research on our platforms. Have questions about partnering? Contact us.

Atom Computing to invest $100 mln in Colorado for quantum computer center

By Jane Lanhee Lee

An Atom Computing's Phoenix quantum computer is seen in Berkeley, California
Colorado Governor Jared Polis attended the opening ceremony of Atom Computing's new facility in Boulder, Colorado

[1/2] An Atom Computing's Phoenix quantum computer is seen in Berkeley, California, July 21, 2022. REUTERS/Jane Lanhee Lee12

Sept 28 (Reuters) - Atom Computing, a Berkeley, California-based quantum computer maker, said on Wednesday it would invest $100 million over the next three years in Colorado where it plans to build its next generation of quantum computers.

It is the latest quantum computing startup to build out its base in Boulder, Colorado. The state started to boost its involvement in quantum computing about two years ago, said Colorado's governor, Jared Polis, who attended Wednesday's Atom Computing event in Boulder.

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"We want to be the leader of quantum computing as this industry creates hundreds of companies, tens of thousands of jobs, and powers a new technology revolution," Polis told Reuters.

Quantum computers, which use quantum mechanics, will eventually be able to operate millions of times faster than today's advanced supercomputers. The technology is still in its early stages.

The University of Colorado Boulder has been a center for quantum physics-related research, and is home to JILA, formerly known as the Joint Institute for Laboratory Astrophysics, a joint institute of the university and the National Institute of Standards and Technology.

Atom Computing uses lasers to control individual atoms and build qubits, the basic unit of quantum information. The company has raised a total of $80 million so far, it said.