Computers have steadily become smaller and more powerful over the past half-century, thanks to the miniaturization of transistors. But as ever-shrinking technology crosses the threshold into the atomic realm, the laws of quantum physics suddenly take hold. While this poses serious hurdles for classical computing, it opens incredible new possibilities in the realm of quantum computing.
Classical computers use binary “bits” of ones and zeros. Quantum computers will encode such bits in physical systems where we can also harness the quantum mechanical properties and obtain a more powerful system of quantum bits, or qubits. Thanks to the amazing rules of quantum mechanics, qubits can be in a “superposition” of zero and one simultaneously. Another quantum property called “entanglement,” which Einstein and others debated decades ago, has since been harnessed in laboratories, and allows us to achieve tasks such as quantum teleportation and squeezing two bits of classical information into a single qubit. Quantum teleportation allows a qubit of information to be transmitted over a distance (indeed, teleported) by sending only two bits of classical information, and has important applications in quantum communication and building robust quantum computers.
Faculty members at the Institute for Quantum Computing (IQC) are exploring the fundamental properties of quantum information. Ashwin Nayak has led pioneering work in quantum coding with random access codes. Debbie Leung’s work has contributed to the refutation of the “additivity conjecture” for quantum channel capacities. Norbert Lütkenhaus, Richard Cleve and John Watrous have made significant discoveries in the theory of communication using qubits.