Quantum bits in space and time


Nowadays, quantum information theory is a well-established part of modern physics. It promises important technological applications in computing and cryptography, and the ways that its abstract notions of information, computation, and complexity are embedded in our world informs our understanding of the fundamental laws of physics.

Gravity is far from the typical playground of the working quantum information theorist. In fact, finding a fully consistent theory of quantum gravity is one of the outstanding problems in physics. Early on, the thermodynamics of black holes gave an important clue: the entropy of a black hole is maximal, but scales only with the area of its horizon – suggesting that the degrees of freedom in a region of space may be equivalently described by an ordinary quantum theory on the region's boundary. This idea is known as the holographic duality.

In the past decade, a striking picture began to form that the way space-time emerges in quantum gravity is – through the holographic duality – intimately connected to the way quantum bits are entangled in a quantum computer. This led to a vibrant new frontier of research at the interface of quantum information, gravity and field theory. Recently, myself and colleagues identified models that for the first time gave a simple conceptual explanation of several key features of the duality in an important special case. This puts me in a unique position to achieve the following objectives, which address some of the outstanding open questions in the field:

1. Clarify the mechanisms relating space-time and entanglement by extending our information-theoretic model of the holographic duality.
2. Determine the ultimate limits of quantum information processing by developing the necessary toolbox of quantum information theory for space-time.
3. Enable novel numerical experiments for quantum field theories by constructing corresponding tensor networks.





Dr. M. Walter

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Stanford University, Department of Physics, Stanford Institute for Theoretical Physics (SITP)


01/09/2017 tot 31/08/2020