Researchers discussed developments in quantum technologies on throughout SPIE Photonics West. On Wednesday 31 January, the presentations centered on technical advances for manipulating light in applications. These incremental advancements contribute to the hardware and application development for future quantum devices such as quantum computers and sensors.

**Takahiro Serikawa**, a graduate student at the University of Tokyo, discussed his group's work on a quantum computation component known as a cubic phase gate during his presentation titled *Quantum information processing with a traveling wave of light*. This component would be used in a quantum computing framework known as one-way quantum computation. A one-way quantum computer would perform a logical operation by measuring properties of its quantum bits, or qubits. The act of measurement instantaneously changes the state of a quantum particle, and researchers are trying to engineer the process to perform computations.

This framework would perform by a different physical process than a standard quantum computer, such as the one currently under development at Google. A standard quantum computer performs operations not by measurement, but by interfering multiple quantum particles.

**Michael Reimer**, a professor at the University of Waterloo, presented a project on quantum communication hardware in a talk titled *Integrated quantum optics with nanowires*. His group has embedded a tiny semiconductor known as a quantum dot, made of indium arsenide phosphide, in a nanowire about half a micron thick. The quantum dot emits entangled photons, which are useful in quantum encryption protocols. The nanowire guides the entangled photons so that a receiver can detect them more efficiently.

**Paolo Mataloni**, a professor at the Sapienza University of Rome, discussed his group's work on quantum simulations. Experts predict that quantum computers should be able to simulate quantum systems such as individual molecules much more easily than classical computers, which require supercomputers even for simple simulations. Mataloni's group has been able to manipulate pairs of photons to imitate two classes of quantum particles known as fermions and bosons.

Manipulating quantum properties is still difficult because quantum properties are extremely delicate. "The experimental challenge is keeping the systems stable," Serikawa said during his presentation.