A scheme for amplification and discrimination of photons

A scheme for exploring photon number amplification and discrimination is presented based on the interaction of a large number of two-level atoms with a single mode radiation field. The fact that the total number of photons and atoms in the excited states is a constant under time evolution in Dicke model is exploited to rearrange the atom-photon numbers. Three significant predictions emerge from our study: Threshold time for initial exposure to photons, time of perception (time of maximum detection probability), and discrimination of first few photon states.Comment: 8 pages, 3 figures, RevteX, Minor revision, References adde

Quantum reading of digital memory with non-Gaussian entangled light

It has been shown recently (Phys. Rev. Lett. 106, 090504 (2011)) that entangled light with Einstein-Podolsky-Rosen (EPR) correlations retrieves information from digital memory better than any classical light. In identifying this, a model of digital memory with each cell consisting of reflecting medium with two reflectivities (each memory cell encoding the binary numbers 0 or 1) is employed. The readout of binary memory essentially corresponds to discrimination of two Bosonic attenuator channels characterized by different reflectivities. The model requires an entire mathematical paraphernalia of continuous variable Gaussian setting for its analysis, when arbitrary values of reflectivities are considered. Here we restrict to a basic quantum read-out mechanism with non-Gaussian entangled states of light, with the binary channels to be discriminated being ideal memory characterized by reflectivity one i.e., an identity channel and thermal noise channel, where the signal light illuminating the memory location gets completely lost (zero reflectivity) and only a white thermal noise hitting the upper side of the memory reaches the decoder. We compare the quantum reading efficiency of entangled light with any classical source of light in this model. We show that entangled transmitters offer better reading performance than any classical transmitters of light in the regime of low signal intensity.Comment: 7 pages, 6 figures, To appear in Phys. Rev.

Extremal primes for elliptic curves without complex multiplication

Fix an elliptic curve E over Q. An extremal prime for E is a prime p of good reduction such that the number of rational points on E modulo p is maximal or minimal in relation to the Hasse bound. Assuming that all the symmetric power L-functions associated to E are automorphic and satisfy the Generalized Riemann Hypothesis, we give the first non-trivial upper bounds for the number of such primes when E is a curve without complex multiplication. In order to obtain this bound, we use explicit equidistribution for the Sato-Tate measure as in the work of Rouse and Thorner (arXiv:1305.5283) and refine certain intermediate estimates taking advantage of the fact that extremal primes have a very small Sato-Tate measure

Joint Measurability and Temporal Steering

Quintino et. al. (Phys. Rev. Lett. 113, 160402 (2014)) and Uola et. al. (Phys. Rev. Lett. 113, 160403 (2014)) have recently established an intrinsic relation between non-joint measurability and Einstein-Podolsky- Rosen steering. They showed that a set of measurements is incompatible (i.e., not jointly measurable) if and only if it can be used for the demonstration of steering. In this paper, we prove the temporal analog of this result viz., a set of measurements are incompatible if and only if it exhibits temporal steering.Comment: 6 pages,no figures, typos corrected, improved presentation; To appear in JOSA B feature issue "80 years of Steering and the Einstein-Podolsky-Rosen Paradox

Contracting for Financial Privacy: The Rights of Banks and Customers Under the Reauthorized Patriot Act

The 2001 Patriot Act chipped away financial privacy protections by allowing law enforcement authorities easier access to bank customer records. Under the Patriot Act, federal authorities may access customer records by issuing formal subpoena-like requests under the Foreign Intelligence Surveillance Act (FISA) or informal national security letters (NSLs) to banks while prohibiting notice to any affected customers. However, the 2006 revisions to the Patriot Act permit banks to challenge FISA requests and NSLs in federal court before releasing customer records. While the Act does not require banks to make these challenges on behalf of their customers, this Paper will argue that the contracts banks sign with their customers – interpreted in light of the banking tradition of confidentiality and the current regime of federal and state privacy protections – obligate banks to review government requests for customer records and file challenges when appropriate. Furthermore, I will argue that banks and customers should be able to enter into contracts explicitly obligating banks to challenge FISA requests and NSLs, and that such contracts would be enforceable and financially feasible

Writing a Life Between Gender Lines Conversations with A. Revathi about her autobiography The Truth About Me: A Hijra Life Story

A. Revathi was born physiologically male but felt and behaved like a girl - this is how she tells her story, as will be clear from the interview below. Nearly her whole childhood, spent in a village in Salem district of Tamil Nadu, was plagued by this deep and nagging unease of being trapped in the wrong body and by 'a growing sense of irrepressible femaleness'. But when she behaved like one of her girl-playmates, it only meant repeated humiliation and violence by her family and community. This affected her academic performance, and she had to drop out of school after failing the tenth grade. In a quest to be true to herself, Revathi, still in her teens, ran away from home and travelled to Delhi to join a house of hijras. Hijras are male-to-female transsexuals who undergo a surgical removal of the genitals (often performed surreptitiously and in unsanitary conditions) and comprise a distinct community across India with elaborate customs and regulations of their own. Hijras are given ritualistic importance by mainstream Indian society (for instance, their blessings are considered to bring good fortune) but at the same time they are easy targets for sexual crimes, discriminated against in public spaces, and have few options for livelihood apart from performing at social events, begging or prostitution. Revathi, now in her mid-forties, discusses all this with remarkable candour and courage in her autobiography The Truth About Me: A Hijra Life Story, translated into English from Tamil by V. Geetha and published by Penguin India Books in 2010. This autobiography is among the very first of its kind in India, uninhibited with regard to divisive gender lines, sexual hypocrisy of 'traditional' societies, and the dismal lack of public discourse on the rights of sexual minorities