Date: 23 January 2013, 4pm
Venue: CQT Seminar Room, S15-03-15
Speaker: Eric Cornell, JILA
Title: A high-energy particle experiment on a tabletop: what you can learn at 100 meV that you can't learn at 100 TeV
Abstract:
Any time anyone has ever measured, the north and south poles of an electron are seen to be identical. But there are good theoretical reasons to suspect that upon closer examination we may find a discrepancy. Observing such a discrepancy would be the equivalent recording a spark chamber track of a never before seen supersymmetric particle. We will take advantage of nature's high-electric-field laboratory -- a polar molecule -- to reach new levels of sensitivity to the electon's hypothetical electric dipole moment.
Date: 21 March 2013, 4pm
Venue: CQT Seminar Room, S15-03-15
Speaker: Miguel Angel Martin-Delgado, Universidad Complutense de Madrid
Title: New Lattice Gauge Theories From Quantum Computation
Abstract:
I present some views and perspectives on the notions of Fault-Tolerant Quantum Computation with topological codes Next, I present current results on how the process of external quantum error correction on topological color codes (TCCs) leads to new versions of LGTs (Lattice Gauge Theories). In particular, we find that:
i/ A complete study of error correction in TCCs yields the error threshold of p_c = 4.5(2)%.
ii/ A novel Abelian lattice gauge theory with gauge group Z_2xZ_2 and a peculiar lattice and gauge structure that departs from the standard formulations of Wegner and Wilson. We refer to it as a tricolored LGT. Its structure reflects the error history in color codes, rather than the discretization of a continuous gauge theory.
iii/ A novel approach to pinpoint first-order phase transitions in LGTs with disorder using the skewness of the average over Wilson loop operators. Finally, we show how to increase the error threshold up to 18.9(3)% when noise correlations are taken into account in depolarizing channels
Date: 4 April 2013, 4pm
Venue: CQT Seminar Room, S15-03-15
Speaker: Masahito Ueda, The University of Tokyo
Title: Information thermodynamics and fluctuation theorems
Abstract:
The second law of thermodynamics presupposes a clear-cut
distinction between the controllable and uncontrollable degrees of
freedom by means of macroscopic operations. The cutting-edge
technologies in quantum information and nanoscience seem to require us
to abondon such a working hypothesis in favor of the distinction between
the accessible and inaccessible degrees of freedom. In this talk, I will
talk about the fundamentals of such information thermodynamics together
with the related new results on fluctuation theorems.
Date: 16 May 2013, 4pm
Venue: CQT Seminar Room, S15-03-15
Speaker: José Ignacio Latorre, Universitat de Barcelona
Title: Quantum Computation of Prime Number Functions
Abstract:
We propose a quantum circuit that creates a pure state corresponding to the quantum superposition of
prime numbers. This {\em Prime} state can be built
using an oracle which is a quantum implementation of the classical Miller-Rabin primality test. The {\em Prime} state is highly entangled, and its entanglement measures encode
number theoretical functions such as the distribution of twin primes or the Chebyshev bias.
This algorithm can be further combined with the quantum Fourier transform to yield an estimate of the prime counting function, more efficiently than any classical algorithm and with an error below the bound that allows for the verification of the Riemann hypothesis. Arithmetic properties of
prime numbers are then, in principle, amenable to experimental verifications on quantum
systems.
Date: 18 July 2013, 4pm
Venue: CQT Seminar Room, S15-03-15
Speaker: Terry Rudolph, Imperial College
Title: To be advised
Date: 25 July 2013, 4pm
Venue: CQT Seminar Room, S15-03-15
Speaker: Jukka Pekola, Aalto University
Title: To be advised
Date: 17 October 2013, 4pm
Venue: CQT Seminar Room, S15-03-15
Speaker: Michael Berry, University of Bristol
Title: To be advised
Date: 28 November 2013, 4pm
Venue: CQT Seminar Room, S15-03-15
Speaker: Masanao Ozawa, Nagoya University
Title: Uncertainty Principle and Quantum Reality
Abstract:
Abstract: In this talk, I will review my proposal to reformulate Heisenberg's uncertainty principle [1-3] and its recent experimental confirmation [6]. The new formulation allows us simultaneous measurements of totally non-commuting observables [4].
We will discuss how this affects our understanding of quantum reality along the line with a recent mathematical reconstruction of Bohr's reply to Einstein-Podolsky-Rosen on their paradox [5].
References.
[1] M. Ozawa, Universally valid reformulation of the Heisenberg
uncertainty principle on noise and disturbance in measurement, Phys. Rev. A 67, 042105/1-042105/6 (2003).
[2] M. Ozawa, Uncertainty principle for quantum instruments and
computing, Int. J. Quant. Inf. 1, 569--588 (2003).
[3] M. Ozawa, Uncertainty relations for noise and disturbance in
generalized quantum measurements, Ann. Phys. (N.Y.) 311, 350-416 (2004).
[4] M. Ozawa, Quantum reality and measurement: A quantum logical
approach, Found. Phys. 41, 592-607 (2011).
[5] M. Ozawa and Y. Kitajima, Reconstructing Bohr's Reply to EPR in
Algebraic Quantum Theory, Found. Phys. 42, 475-487 (2012).
[6] J. Erhart, S. Sponar, G. Sulyok, G. Badurek, M. Ozawa, and Y.
Hasegawa, Experimental demonstration of a universally valid error-disturbance uncertainty relation in spin-measurements, Nature Phys. 8,
185-189 (2012).
