Quantum Computing Milestone Achieved

Researchers at ORNL perform independent operations on two qubits encoded on photons of different frequencies.

Research scientists at the US Department of Energy's Oak Ridge National Laboratory (ORNL) have performed an important step in the evolution of quantum computing, demonstrating “a new level of control over photons encoded with quantum information."

According to the announcement, “Joseph Lukens, Brian Williams, Nicholas Peters, and Pavel Lougovski, research scientists with ORNL’s Quantum Information Science Group, performed distinct, independent operations simultaneously on two qubits encoded on photons of different frequencies, a key capability in linear optical quantum computing.”

The experiment used two entangled photons contained in a single strand of fiber-optic cable, which Lougovski called “the smallest quantum computer you can imagine.”

The paper, which was published in Optica, explores a frequency-based approach to quantum computing. According to Lukens, “A lot of researchers are talking about quantum information processing with photons, and even using frequency. But no one had thought about sending multiple photons through the same fiber-optic strand, in the same space, and operating on them differently.”

Williams adds, “When the photons are taking different paths in the equipment, they experience different phase changes, and that leads to instability. When they are traveling through the same device, in this case, the fiber-optic strand, you have better control.”