Quantum Milestone: Turning a Corner with Trapped Ions

July 11, 2022

Quantinuum

When it comes to transporting ions, researchers at Quantinuum have turned a corner.  Both literally and figuratively.

The Quantinuum team can now move two different types of ions through a junction in a surface trap, a tiny electrode-filled device at the heart of trapped ion quantum computers.

In a pre-print publication posted on arXiv, Quantinuum researchers outlined how they developed new waveforms that can guide a pair of ytterbium and barium ions through an intersection without the charged particles becoming overly excited or flying out of the trap.   

The team tested the technique on a prototype trap with a grid-like architecture that Quantinuum has designed and microfabricated. This trap design will be a central part of future quantum computers such as the System Model H3.   

This feat is an important breakthrough in the world of trapped ion quantum computing and for Quantinuum.

The ability to transport paired ions through a junction at the same time and intact is critical for scaling trapped ion systems.  It’s also a longstanding technical challenge that trapped ion researchers in academia, government and industry have sought to solve for years.

“What Quantinuum has accomplished is a significant breakthrough for the field of trapped ion research and for our technology,” said Tony Uttley, president, and chief operating officer at Quantinuum.  “This will enable us to deliver faster quantum computers with more qubits and fewer errors.”

Smooth transport of ions

Quantinuum’s technologies are based on the Quantum Charged Coupled Device (QCCD) architecture, a concept first introduced  by the Ion Storage Group at the National Institute of Standards and Technology (NIST) in the early 2000s.

Like other trapped ion technologies, this architecture relies on traps to capture ions in electric fields - or wells.  Gates are performed on small chains of ions, which can be reordered and reconfigured within the architecture, enabling all-to-all connectivity.

In Quantinuum’s System Model H1 technologies, each well contains an ytterbium ion and a barium ion.  The ytterbium ion functions as a qubit while the barium is cooled with a laser to reduce the motions of both ions, a technique known as sympathetic cooling. This cooling makes it possible to maintain low error rates in quantum computing operations for long calculations.

The H1-1 and H1-2 machines currently use a trap with a simple geometry or design that resembles railroad tracks.  Wells of ions are moved back and forth along these linear tracks and swapped as needed to run an algorithm.  

This linear design works well with fewer qubits. But it has limitations that make scaling difficult.  Adding hundreds, much less thousands of qubits, would require the tracks to be much longer. It also would take more time to reposition and reset qubits.

To overcome these challenges, Quantinuum researchers have proposed moving to traps with more complex geometries.  The System Model H2 will incorporate a racetrack-like design. The System Model H3 and beyond will use two-dimensional traps that resemble a city street grid with multiple railroad lines and intersections.

This design, however, also poses challenges.  Getting those tracks to behave well at intersections is difficult and can jar ions and cause unwanted motion – especially those with different masses.  It is somewhat like maneuvering a bullet train and allowing it to turn left or right at 90 degrees, or continue moving straight, without causing the cars to rock.

Quantinuum researchers were able to turn an ytterbium-barium ion pair around sharp corners with little motion.  Until now, researchers envisioned having to separate paired ions and move them through junctions one a time, which would dramatically slow the operation.  “To our knowledge, this is the first time any team has simultaneously moved two different species of ions through a junction in a surface trap,” said Dr. Cody Burton, a senior advanced physicist who worked on the project and lead author of the arXiv paper.    

What’s next?

Researchers will continue to test and refine this new method.  

Their goal is to expand from moving a single well to transporting several through multiple junctions at the same time.  From there, they plan to incorporate this methodology into the System Model H3, which is expected to be the first Quantinuum quantum technology with the two-dimensional, grid-like trap.
“This new configuration will be key for scaling quantum computers in the hundreds, and then thousands, of high-fidelity qubits,” Uttley said.  “While scaling, the qubits will maintain the high-quality characteristics such as low gate errors, long coherence times, and low cross-talk for which Quantinuum’s technologies are known.”

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Kaniah Konkoly-Thege

Kaniah is Chief Legal Counsel and SVP of Government Relations for Quantinuum. In her previous role, she served as General Counsel, Honeywell Quantum Solutions. Prior to Honeywell, she was General Counsel, Honeywell Federal Manufacturing and Technologies, LLC, and Senior Attorney, U.S. Department of Energy. She was Lead Counsel before the Civilian Board of Contract Appeals, the Merit Systems Protection Board, and the Equal Employment Opportunity Commission. Kaniah holds a J.D. from American University, Washington College of Law and B.A., International Relations and Spanish from the College of William and Mary.

Jeff Miller

Jeff Miller is Chief Information Officer for Quantinuum. In his previous role, he served as CIO for Honeywell Quantum Solutions and led a cross-functional team responsible for Information Technology, Cybersecurity, and Physical Security. For Honeywell, Jeff has held numerous management and executive roles in Information Technology, Security, Integrated Supply Chain and Program Management. Jeff holds a B.S., Computer Science, University of Arizona. He is a veteran of the U.S. Navy, attaining the rank of Commander.

Matthew Bohne

Matthew Bohne is the Vice President & Chief Product Security Officer for Honeywell Corporation. He is a passionate cybersecurity leader and executive with a proven track record of building and leading cybersecurity organizations securing energy, industrial, buildings, nuclear, pharmaceutical, and consumer sectors. He is a sought-after expert with deep experience in DevSecOps, critical infrastructure, software engineering, secure SDLC, supply chain security, privacy, and risk management.

Todd Moore

Todd Moore is the Global Vice President of Data Encryption Products at Thales. He is responsible for setting the business line and go to market strategies for an industry leading cybersecurity business. He routinely helps enterprises build solutions for a wide range of complex data security problems and use cases. Todd holds several management and technical degrees from the University of Virginia, Rochester Institute of Technology, Cornell University and Ithaca College. He is active in his community, loves to travel and spends much of his free time supporting his family in pursuing their various passions.

John Davis

Retired U.S. Army Major General John Davis is the Vice President, Public Sector for Palo Alto Networks, where he is responsible for expanding cybersecurity initiatives and global policy for the international public sector and assisting governments around the world to prevent successful cyber breaches. Prior to joining Palo Alto Networks, John served as the Senior Military Advisor for Cyber to the Under Secretary of Defense for Policy and served as the Acting Deputy Assistant Secretary of Defense for Cyber Policy.  Prior to this assignment, he served in multiple leadership positions in special operations, cyber, and information operations.