Researcher Prem Kumar, the AT&T Professor of Information Technology in
the Department of Electrical Engineering and Computer Science and the director
of the Center for Photonic Communication and Computing, and his research team
are now one step closer to making quantum computers a reality.
Kumar and his team have demonstrated
a basic building block of a quantum computer using entangled photons
generated in optical fibers. Kumar says, “Because it is done with fiber and the
technology that is already globally deployed, we think that it is a significant
step in harnessing the power of quantum computers.”
With the computers we use today, data is processed in bits that consist of
ones and zeros, or on and off states. In quantum computing, quantum bits, also
known as qubits, are used that can exist in a one or zero state as well as a
third state known as a “superposition.” This superposition is where a quantum
computer gets the huge performance gains over current, traditional computers.
The superposition allows the qubit to be both a one and zero simultaneously
allowing the computer to process more information, much faster than computers
Kumar and his team used a pair of photons and have been able to entangle the
pair of photons in an optical fiber using the fiber’s nonlinear response. The
researchers also say that the photons remain “mysteriously” entangled no matter
how far you separate the two in the transmission fibers.
In the project, Kumar and his team were able to use the photons to perform a
basic quantum computer task, a controlled-NOT gate, allowing two photonic
qubits to interact. Kumar said in a statement, “This device that we
demonstrated in the lab is a two-qubit device — nowhere near what’s needed for
a quantum computer — so what can you do with it? It’s nice to demonstrate
something useful to give a boost to the field, and there are some problems at
hand that can be solved right now using what we have."
DailyTech reported in October of 2007 that another team of
researchers working on quantum computing had been able to devise a method of controlling
the spin of single electrons.