Department of Physics at the U of I

AMO/Quantum Physics

Entangled photons
Photo by Professor Paul Kwiat, University of Illinois at Urbana-Champaign and Michael Reck, University of Vienna

What is Quantum Physics?

Quantum information science is the study of the often-bizarre-seeming features of quantum mechanics and their application to problems in information processing. These features include wave-particle duality, the principle of superposition, the intrinsic randomness of quantum mechanical measurement outcomes, and the phenomenon of entanglement. (Entanglement refers to the nonlocal correlation that can exist between quantum mechanical systems, even when the components are separated by large distances.) These phenomena are being applied to such tasks as quantum computation (which could allow an incredible speed-up over classical computation for certain types of problems); quantum cryptography (the only provably secure method of encryption, whose security is guaranteed by the laws of physics); and quantum metrology (by which measurements can be made with resolutions exceeding those allowed by classical physics).

What Are We Doing With Quantum Physics at the U of I?

Here at the University of Illinois at Urbana-Champaign, we are learning how to gain control over these exquisitely sensitive quantum systems. Photons, the tiny bundles that light travels in, act as our window into the quantum world. By using lasers as a source for our photons, we take advantage of one of their special properties: all of the photons emitted from a particular laser are quantum-mechanically identical. This allows the systematic study of how quantum systems react to manipulation, interaction with themselves, and measurement. In addition to investigating these individual photons, we can also create pairs of entangled photons. Each photon in an entangled pair contains information which is totally random, yet perfectly correlated with that of its partner. This seemingly paradoxical behavior is the essence of how quantum mechanics differs from classical mechanics. Our entangled photon source allows us to study the rudiments of quantum computing, is crucial to experiments in quantum cryptography, and provides extremely convincing evidence that the universe does not obey classical laws.

Faculty

Baym, Gordon A Research Professor 337C Loomis Laboratory 217.333.4363	Ceperley, David M Professor 2107 Engineering Sciences Building 217.244.0646
Demarco, Brian L Associate Professor 329 Loomis Laboratory 217.244.9848	Kwiat, Paul G Professor 337B Loomis Laboratory 217.333.9116
Nayfeh, Munir Professor 407 Loomis Laboratory 217.333.3774	Van Harlingen, Dale J Professor 211 Loomis Laboratory 217.333.3760
Vishveshwara, Smitha Associate Professor 2109 Engineering Sciences Building 217.333.4370
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