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Quantum Information

Quantum Information at SITP

One of the defining features of quantum mechanics is the Heisenberg Uncertainty Principle, which imposes unbreakable limits on our knowledge of reality. Despite these restrictions, quantum mechanical particles can do amazing things like exist at two different locations at the same time. Quantum information science aims to explore the nature of information at the quantum level, a world in which bits can be both zero and one at the same time and perfect copying is impossible.

At the practical level, quantum information powers forms of secure communication that are provably impossible in a “classical” world.  Likewise, an intrinsically quantum-mechanical computer could efficiently solve problems that are intractable for any computer of more traditional design, the most notorious example being that a quantum computer could crack most of the codes used to secure the internet.

Quantum information researchers at SITP have played an important role in the development of the basic theory of quantum communication. They continue to search for better ways to protect quantum computers from noise and communications from prying eavesdroppers. A unique feature of the quantum information group at SITP, however, is its close integration and participation in research on quantum gravity and black holes. Stanford is at the forefront of exploring the role of quantum entanglement to the geometry of space, the importance of quantum error correction in black hole evaporation, and even the relevance of computational complexity to stability of space.

 

Video Brief

Patrick Hayden | Decoding Spacetime

When Shannon formulated his groundbreaking theory of information in 1948, he did not know what to call its central quantity, a measure of uncertainty. It was von Neumann who recognized Shannon’s formula from statistical physics and suggested the name entropy. This was but the first in a series of remarkable connections between physics and information theory.

Entanglement and Complexity: Gravity and Quantum Mechanics

Professor Leonard Susskind describes how gravity and quantum information theory have come together to create a new way of thinking about physical systems. From fluid dynamics to strange metals, from black holes to the foundations of quantum mechanics, almost all areas of physics are being touched by the new paradigm.

"ER = EPR" or "What's Behind the Horizons of Black Holes?" (Lecture 2)

ER = EPR is a shorthand that joins two ideas proposed by Einstein in 1935. One involved the paradox implied by what he called “spooky action at a distance” between quantum particles (the EPR paradox, named for its authors, Einstein, Boris Podolsky and Nathan Rosen). The other showed how two black holes could be connected through far reaches of space through “wormholes” (ER, for Einstein-Rosen bridges). At the time that Einstein put forth these ideas — and for most of the eight decades since — they were thought to be entirely unrelated.

"ER = EPR" or "What's Behind the Horizons of Black Holes?" (Lecture 1)

ER = EPR is a shorthand that joins two ideas proposed by Einstein in 1935. One involved the paradox implied by what he called “spooky action at a distance” between quantum particles (the EPR paradox, named for its authors, Einstein, Boris Podolsky and Nathan Rosen). The other showed how two black holes could be connected through far reaches of space through “wormholes” (ER, for Einstein-Rosen bridges). At the time that Einstein put forth these ideas — and for most of the eight decades since — they were thought to be entirely unrelated.

News Item

The first It From Qubit collaboration workshop and summer school was held at the Perimeter Institute in

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