A Quantum Network of Clocks

June 16, 2014
World-wide quantum clock network

The concept of world-wide quantum clock network: Illustration of a cooperative clock operation protocol in which individual parties (for example, satellite-based atomic clocks from different countries) jointly allocate their respective resources in a global network involving entangled quantum states. This guarantees an optimal use of the global resources, achieving an ultra-precise clock signal limited only by the fundamental bounds of quantum metrology and, in addition, guaranteeing secure distribution of the clock signal. b. [Figure reprinted by permission from Macmillan Publishers Ltd: P. Kómár, E. M. Kessler, M. Bishof, L.


Two Steps Forward, One Step Back

June 12, 2014

The rich get richer: Gain (purple points) and loss (yellow points) as a function of pre-test score. The more prior knowledge students have, the more concepts they gain during their course of study and the fewer they lose. [Figure reprinted by permission from Macmillan Publishers Ltd: N. Lasry, J. Guillemette, E. Mazur, "Two steps forward, one step back," Nature Physics 10, 402–403(2014) | doi:10.1038/nphys2988 ©2014.]


The Dynamics of Quantum Criticality Revealed by Quantum Monte Carlo and Holography

June 12, 2014
Figure 4: Holographic continuation

Holographic continuation: a, The black points represent Monte Carlo data for the conductivity at the superfluid–insulator QCP at imaginary frequencies. b, Real part of the holographic conductivity evaluated at complex frequencies, where the imaginary/real axis dependence is highlighted by the green/blue line. The arrow represents the continuation procedure. c, Resulting conductivity at real frequencies (solid blue line). The dashed line is the vortex-like response obtained for γ =−0.08. [Figure reprinted by permission from Macmillan Publishers Ltd: W. Witczak-Krempa, E.S. Sørensen, S.


Electron-Hole Asymmetric Integer and Fractional Quantum Hall Effect in Bilayer Graphene

June 5, 2014
Fractional quantum Hall states in bilayer graphene

Fractional quantum Hall states in bilayer graphene: (A and C) Inverse compressibility as a function of filling factor and magnetic field. The color scales are the same in both panels. (B and D) Average inverse compressibility between B = 7.9 and 11.9 T as a function of filling factor. Colors indicate regions of similar behavior in the background inverse compressibility. (E and F) Inverse compressibility as a function of filling factor and magnetic field near ν = 7/5 and 3/5.


ProtonMail: an 'NSA-Proof' Encrypted Email

May 21, 2014

Graduate student Andy Yen is one of the founders of ProtonMail: the first end-to-end encrypted email service which is web based and easy to use.  PhotonMail is said to be so secure that its data is inaccessible even to ProtonMail's own servers and and thus cannot be cracked by third parties.  The Beta version of the service was released on May 16; the response has been so overwhelming that new signups are already on hold while the company is launching additional servers.



Professor Mazur Wins Minerva Prize

May 20, 2014
Prof. Eric Mazur

Prof. Eric Mazur is the first winner of the Minerva Prize for Advancements in Higher Education. In recognizing Dr. Mazur for his significant contributions to improving higher education, the Minerva Academy specifically noted his development of Peer Instruction, an innovative teaching method that incorporates interactive pedagogy into the classroom and has been recognized worldwide for driving dramatic improvements in student learning.


Fermi Surface and Pseudogap Evolution in a Cuprate Superconductor

May 15, 2014
Schematic of the high-DOS regions which contribute to QPI

Superconductivity arises from pairing of electrons on the Fermi surface. Professors Jenny Hoffman and Subir Sachdev, with colleagues from Harvard, MIT, Nagoya University, and Northeastern University report in Science that they used Fourier transform STM to map a small-to-large Fermi surface transition in the cuprate superconductor Bi2-yPbySr2-xLaxCuO6+d, demonstrating a quantum critical point near optimal doping at zero field. The researchers showed that superconductivity coexists with the pseudogap on the recovered antinodal Fermi surface above optimal doping.