At Cornell University, Peter McMahon, Applied and Engineering Physics, studies the physics of computation, and is laying the foundation for future state-of-the-art quantum computers.
"We study the physics of computation, and in particular we try to explore how physical processes can be harnessed to design or build more efficient computers than what we have currently. An example of this is quantum computation, where one is trying to take advantage of the complexity of quantum mechanics to design computers that can do tasks that are extremely difficult for conventional, classical computers."
Computers today perform calculations using "bits," units of information that can have only one of two values, 0 or 1. Physically, a bit can be represented by a voltage in a microchip, magnetism in a hard disk, or even a hole in a paper card. By comparison, quantum computers manipulate "qubits," the quantum equivalent of bits. Qubits, like bits, can be in a state of 0 or 1. However, qubits can also be in any combination of these two states, called a superposition.
Because qubits can exist in superposition, a classical computer would require exponentially many numbers to represent the state of multiple qubits. This exponential size of the states in a quantum computer is partially what gives quantum computers their power versus classical computers.
The McMahon lab is creating qubits in several different physical systems, but their main focus is on two platforms: superconducting circuits and quantum-optical devices. Aside from directly building quantum computing hardware, the lab studies future applications for quantum computers.
"We're interested in a number of different applications of novel computing technologies, and they fall broadly within three categories: machine learning, optimization, and quantum simulation. And we are now entering an exciting era in which we can actually start to explore ideas that people have had for many years experimentally, and try to find how well quantum machines in the near term can actually help us perform quantum simulation tasks."