New photonic chip offers route to specialized quantum computing

University of Washington device employs eight photonic cavities as quantum simulator.

Development of quantum computing devices promises to be transformational in multiple applications, including security, drug discovery and material fabrication.

One facet of current research involves the creation of specialized quantum computer devices termed “quantum simulators,” special purpose devices dedicated to the tackling of defined specific problems rather than act as generally programmable computing devices.

Various approaches to quantum simulators suitable for practical real-world tasks have been tried, based on exotic quantum operations, trapped ions, cold atoms and superconducting qubits.

A project at the University of Washington (UW) has now demonstrated that a new kind of silicon photonic chip could function as the foundation of a practical quantum simulator, and published its findings in Nature Communications.

“We have shown that photonics is a contender for quantum simulation, and photonic chips are a reality,” commented Arka Majumdar from UW. “We believe that these chips can play a very important role in building a quantum simulator.”

The work builds on the use of photonic coupled cavities arranged in arrays, where coupling effects between cavities constrain the movement of photons for long enough that useful non-linear effects can occur. UW’s new implementation employs a lattice made up of eight photonic resonators, where photons can be confined, raised and lowered in energy through the application of thermal energy, and moved around in a controlled manner, essentially forming circuits.

In practice this involved UW designing an algorithm that to map the chip in detail, and designing a new kind of architecture for heating and independently controlling each cavity in the array in order to program the device. Successfully implementing both of these two innovations on a silicon photonic chip has never been accomplished before, according to the UW team.