Why it matters: Quantum computers promise to tackle problems that stump even the most advanced supercomputers. Getting there is a different story, though. One of the biggest hurdles is efficiently connecting multiple quantum processors so they can share information without errors. A new interconnect device by MIT researchers could solve this problem.
Current quantum-computing systems rely on clunky “point-to-point” connections, where data is transferred in a chain and has to jump between nodes. Unfortunately, each hop also increases the likelihood of errors.
To address this issue, MIT researchers developed a quantum interconnect component that lets superconducting processors talk directly to each other without a “middleman.” The device uses microwave photons to shuttle data, and it could finally pave the way for a scalable, error-resistant quantum supercomputer.
At the heart of this breakthrough is a superconducting wire (a waveguide), which acts as a quantum highway that lets the photons zip between processors. The team connected two quantum modules to this waveguide, allowing them to send and receive photons on demand. Each module contains four qubits that act as an interface and convert photons into usable quantum data.
Developing accurate, scalable quantum computers involves the creation of remote entanglement. This bizarre phenomenon links two quantum particles that instantly match each other’s state regardless of distance. Entangled qubits act as a single system, enabling mind-bending algorithms that traditional computers could never perform.
Unfortunately, simply firing full photons back and forth doesn’t enable entanglement. Therefore, the researchers devised an odd process that stops the emission process halfway. Doing this leaves the system in a weird quantum limbo where the photon is paradoxically emitted and retained simultaneously. When the receiving module absorbs this “half-photon,” the two processors become entangled – even though they’re not physically linked.
The researchers also have to deal with photon distortion as they travel, which makes them more challenging to capture. To address this problem, the team trained an algorithm to tweak the photon’s shape for maximum absorption. The result was a 60-percent success rate – high enough to confirm genuine entanglement. These results are similar to Oxford’s method, which uses an ion trap to create successful entanglement 70 percent of the time.
The implications are enormous. Unlike today’s patchwork quantum setups, this architecture supports “all-to-all” connectivity, meaning any number of processors can communicate directly. Future improvements like 3D integration or faster protocols could also increase absorption rates.
“In principle, our remote entanglement generation protocol can also be expanded to other kinds of quantum computers and bigger quantum internet systems,” Aziza Almanakly, an electrical engineering and computer science graduate student, concluded.
The team recently published its research in Nature Physics. It’s also worth noting that the US Army Research Office, AWS Center for Quantum Computing, and the US Air Force Office of Scientific Research funded MIT’s efforts.
Image credit: Ella Maru Studio