[quantum-info] This week's notices (talk tomorrow, upcoming workshop at NTU Singapore and more)

[William Matthews]

Upcoming Workshop:

The 5th Asia-Pacific Workshop on Quantum Information Science
25-28 May 2011
Nanyang Executive Centre, NTU, Singapore 
http://www.ntu.edu.sg/ias/upcomingevents/SSQISC11/Pages/default.aspx

**** This Week:

** Talks

Joonwoo Bae - Korea Institute for Advanced Study (KIAS)
Monday Feb. 7, 4:00 pm. Room 405 PI.
"Quantum correlations in applications and foundations"
Quantum key distribution (QKD) is an application of quantum theory as its security relies on quantum foundations, at the same time there is development in the information-theoretic point of view to quantum theory. The security is related to impossible quantum performance, for instance, neither perfect quantum cloning nor perfect quantum state discrimination are possible. In this talk, I would like to discuss issues relevant to practical and fundamental sides of QKD: i) toward characterization of quantum correlations from which a secret key can be distilled, ii) determination whether quantum states shared by two honest parties in distance are entangled or separable, and iii) limitations on quantum performance by fundamental principles in quantum theory.


Prof. Shunlong Luo - Academy of Mathematics and Systems Science Chinese Academy of Sciences 
Tuesday Feb. 8, 12:00 noon. Room 2009 IQC (RAC1). 
"Decorrelation and Decoherence"
Decoherence, interpreted broadly, is essentially the leakage of system information into environment, and is often accompanied by dissipation. The basic question arises as how to quantify decoherence induced by an operation, and how to quantitatively compare decoherence induced by different operations. In this talk, based on a joint ancilla-system-environment tripartite purification for the initial system state and the operation, and by exploiting the intrinsic relations between the loss of correlations in the ancilla-system and the correlations established in the system-environment, we characterize and quantify decoherence via decorrelation.
For this purpose, we first address the issue of separating and quantifying the classical and quantum parts
of decorrelation. With the help of quantum decorrelation, we introduce an intuitive measure of (quantum) decoherence. We further employ these informational quantities to analyze some widely used channels. Our analysis illustrate the intriguing interplay between classical and quantum decorrelations, and shed some light on the informational nature of decoherence.

Vadim Makarov - Norwegian University of Science and Technology
Thursday Feb. 10, 12:00 noon. Room 2009 IQC (RAC1).
"Cracking commercial quantum cryptography"
Quantum cryptography, unbreakable in principle, can currently be hacked through implementation loopholes. I present a recently explored detector control loophole, where a bright light is used by an eavesdropper to induce clicks in single-photon detectors deterministically. This allows a perfect attack, delivering the eavesdropper a full secret key without alerting legitimate users. We have shown that this loophole is present in both commercial quantum key distribution systems currently available on the market (manufactired by ID Quantique, Switzerland and MagiQ Technologies, USA). Also, we have demonstrated a full attack on an entanglement-based research system built at the National University of Singapore.
The talk will include an equipment demonstration of detector control by an eavesdropper.

** Visitors

Lars Lydersen from Norwegian University of Science and Technology (NTNU)
at IQC from Feb. 2, 2011 to Feb. 8, 2011
hosted by Norbert Luetkenhaus

Akira SaiToh
from Kinki University
at IQC from Feb. 5, 2011 to Feb. 9, 2011
hosted by Michele Mosca

Frederic Magniez
from Université Paris Diderot - Paris 7
at IQC & PI from January 29th 2011 to February 11th 2011
hosted by Ashwin Nayak

Vadim Makarov
from Norwegian University of Science and Technology (NTNU)
at IQC from Feb. 2, 2011 to Feb. 12, 2011
hosted by Norbert Luetkenhaus

Joonwoo Bae
from Korea Institute for Advanced Study (KIAS), 
at IQC & PI from February 6th 2011 to February 12th 2011
hosted by Michele Mosca

Lidia del Rio
from ETH Zurich
at PI from January 28th 2011 to February 19th 2011
hosted by Roger Colbeck

Dr. Jianming Cai from Institut für Theoretische Physik
at IQC from Jan. 26, 2011 to Feb. 27, 2011
hosted by Marco Piani

**** Upcoming (next month, not necessarily complete!):

** Talks

Feb. 16, 2:00 pm: Zhengcheng Gu (KITP)
"Tensor-net states: a new perspective on many-body quantum systems"
Room 405 PI
http://pirsa.org/11020083/

Feb. 16, 4:00 pm: Sam Ocko (MIT) 
"TBA"
Room 405 PI
http://pirsa.org/11020102/

Mar. 7, 4:00 pm: Sergio Boixo (Harvard University)
"TBA"
Room 405 PI
http://pirsa.org/11030085/

** Visitors

Sam Ocko from MIT, hosted by Roger Colbeck
February 15th 2011 through February 18th 2011 - Quantum Information

Jay Olson from University of Queensland, hosted by Nicolas Menicucci
February 20th 2011 through March 6th 2011 - Quantum Information

Sergio Boixo from Harvard University, hosted by John Berlinsky
March 6th 2011 through March 11th 2011 - Quantum Information, Other