Physicists Demonstrate a Quantum Processor and Quantum Memory on a Chip

The breakthrough could one day lead to greatly enhanced processing power for robots and other intelligent devices.

Matteo Mariantoni, who conducted the research on a quantum processor. Using the so-called quantum von Neumann machine Mariantoni and his team developed, two qubits are coupled to a quantum bus, realizing a quCPU. Each qubit is accompanied by a quantum memory as well as a zeroing register. The quantum memories together with the zeroing register realize the quRAM. (Credit: George Foulsham, Office of Public Affairs, UCSB)

A new paradigm in quantum information processing has been demonstrated by physicists at UC Santa Barbara.

The researchers demonstrated a quantum integrated circuit that implements the quantum von Neumann architecture. In this architecture, a long-lived quantum random access memory can be programmed, using a quantum central processing unit, all constructed on a single chip, providing the key components for a quantum version of a classical computer.

The UCSB hardware is based on superconducting quantum circuits, which must be cooled to very low temperatures in order to display quantum behavior. The architecture represents a significant development in the field of quantum information processing, and shows that quantum large-scale-integration is within reach.

The quantum integrated circuit includes two quantum bits (qubits), a quantum communication bus, two bits of quantum memory, and a resetting register, comprising a simple quantum computer. "Computational steps take a few billionths of a second, comparable to a classical computer, but the great power is that a quantum computer can perform a large number of calculations simultaneously," said Matteo Mariantoni, postdoctoral fellow in the Department of Physics. "In our new UCSB architecture we have explored the possibility of writing quantum information to memory, while simultaneously performing other quantum calculations.

"On the quantum von Neumann architecture, we were able to run the quantum Fourier transform and a three-qubit Toffoli gate –– key quantum logic circuits for the further development of quantum computing," said Mariantoni.

The UCSB experiment was pursued primarily by Mariantoni, under the direction of Andrew N. Cleland and John M. Martinis, both professors of physics. Mariantoni was supported in this work by an Elings Prize Fellowship in Experimental Science from UCSB's California NanoSystems Institute.

SOURCE: University of California at Santa Barbara