Quantum computers promise to solve many of the world’s toughest problems faster and more efficiently than today’s computers.
However, building bigger and more interconnected quantum computers has been a significant challenge.
Researchers at the University of Chicago’s Pritzker School of Molecular Engineering (PME) have made a breakthrough by combining two powerful technologies: trapped atom arrays and photonic devices.
This new approach could lead to advanced systems for quantum computing, simulation, and networking, making it easier to scale up quantum systems.
“We have merged two technologies which, in the past, have really not had much to do with each other,” said Hannes Bernien, Assistant Professor of Molecular Engineering and senior author of the new study published in Nature Communications.
“It is not only fundamentally interesting to see how we can scale quantum systems in this way, but it also has a lot of practical applications.”
One popular way to build quantum processors is by using arrays of neutral atoms trapped in optical tweezers—highly focused laser beams that hold the atoms in place.
These grids of atoms, when excited in a specific sequence, enable complex quantum computations that can be scaled up to thousands of qubits.
However, these quantum states are fragile and can be easily disrupted, especially by photonic devices that collect data in the form of photons.
“Connecting atom arrays to photonic devices has been quite challenging because of the fundamental differences in the technologies.
Atom array technology relies on lasers for their generation and computation,” explained Shankar Menon, a PME graduate student and co-first author of the new study. “As soon as you expose the system to a semiconductor or a photonic chip, the lasers get scattered, causing problems with the trapping of atoms, their detection, and the computation.”
In their new work, Bernien’s group developed a semi-open chip geometry that allows atom arrays to interface with photonic chips, overcoming these challenges. With this new platform, quantum computations can be carried out in a computation region. Then, a small portion of the atoms containing the desired data can be moved to a new interconnect region for integration with the photonic chip.
“We have two separate regions that the atoms can move between: one away from the photonic chip for computation and another near the photonic chip for interconnecting multiple atom arrays,” explained co-first author Noah Glachman, a PME graduate student. “The way this chip is designed, it has minimal interaction with the computational region of the atom array.”
In the interconnect region, the qubit interacts with a microscopic photonic device, which can extract a photon. The photon can then be transmitted to other systems through optical fibers. This means that many atom arrays could be interconnected to form a larger quantum computing platform than is possible with a single array.
An additional strength of the new system—which could lead to especially speedy computation abilities—is that many nanophotonic cavities can be simultaneously connected to one single atom array. “We can have hundreds of these cavities at once, and they can all be transmitting quantum information at the same time,” said Menon. “This leads to a massive increase in the speed with which information can be shared between interconnected modules.”
While the team has demonstrated the feasibility of trapping an atom and moving it between regions, they are planning future studies to explore other steps in the process. This includes the collection of photons from the nanophotonic cavities and the generation of entanglement over long distances.
This innovative approach of combining trapped atoms and photonics opens up new possibilities for developing large-scale, interconnected quantum systems, bringing us closer to realizing the full potential of quantum computing.
