Spin-Space Entanglement Transfer and Quantum Statistics

Both the topics of entanglement and particle statistics have aroused enormous research interest since the advent of quantum mechanics. Using two pairs of entangled particles we show that indistinguishability enforces a transfer of entanglement from the internal to the spatial degrees of freedom without any interaction between these degrees of freedom. Moreover, sub-ensembles selected by local measurements of the path will in general have different amounts of entanglement in the internal degrees of freedom depending on the statistics (either fermionic or bosonic) of the particles involved.Comment: 5 figures. Various changes for clarification and references adde

Optimal State Discrimination Using Particle Statistics

We present an application of particle statistics to the problem of optimal ambiguous discrimination of quantum states. The states to be discriminated are encoded in the internal degrees of freedom of identical particles, and we use the bunching and antibunching of the external degrees of freedom to discriminate between various internal states. We show that we can achieve the optimal single-shot discrimination probability using only the effects of particle statistics. We discuss interesting applications of our method to detecting entanglement and purifying mixed states. Our scheme can easily be implemented with the current technology

Geometrical effects on energy transfer in disordered open quantum systems

We explore various design principles for efficient excitation energy transport in complex quantum systems. We investigate energy transfer efficiency in randomly disordered geometries consisting of up to 20 chromophores to explore spatial and spectral properties of small natural/artificial Light-Harvesting Complexes (LHC). We find significant statistical correlations among highly efficient random structures with respect to ground state properties, excitonic energy gaps, multichromophoric spatial connectivity, and path strengths. These correlations can even exist beyond the optimal regime of environment-assisted quantum transport. For random configurations embedded in spatial dimensions of 30 A and 50 A, we observe that the transport efficiency saturates to its maximum value if the systems contain 7 and 14 chromophores respectively. Remarkably, these optimum values coincide with the number of chlorophylls in (Fenna-Matthews-Olson) FMO protein complex and LHC II monomers, respectively, suggesting a potential natural optimization with respect to chromophoric density.Comment: 11 pages, 10 figures. Expanded from the former appendix to arXiv:1104.481

Time Averaged Quantum Dynamics and the Validity of the Effective Hamiltonian Model

We develop a technique for finding the dynamical evolution in time of an averaged density matrix. The result is an equation of evolution that includes an Effective Hamiltonian, as well as decoherence terms in Lindblad form. Applying the general equation to harmonic Hamiltonians, we confirm a previous formula for the Effective Hamiltonian together with a new decoherence term which should in general be included, and whose vanishing provides the criteria for validity of the Effective Hamiltonian approach. Finally, we apply the theory to examples of the AC Stark Shift and Three- Level Raman Transitions, recovering a new decoherence effect in the latter.Comment: 7 pages, 2 figure

Sustainability and professional sales: a review and future research agenda

Sustainability has become a consideration for every firm operating in today’s business landscape. Scholars are tasked with uncovering bridges and barriers to successfully implement sustainability strategies, and the academic community has largely responded. However, while sustainability research has proliferated across business disciplines, it is conspicuously missing from professional selling and sales management. This is partly due to conceptual ambiguity, but also because sustainability generally involves firm-level policies and programs, and therefore domains like consumer behavior, marketing strategy, and supply chain management have occupied the space. This is problematic because while executives develop sustainability strategies, the sales force is responsible for conveying those priorities to external stakeholders. Therefore, the goals of our manuscript are to: 1) organize and refine the definition of sustainability in a professional selling context, 2) review relevant literature that examines sustainability in that context, 3) explore emergent themes from this review that 4) reveal gaps in our understanding, and 5) present a research agenda for sales scholars to bridge these gaps and advance our understanding of the role of sustainability in sales and vice versa

Entanglement Controlled Single-Electron Transmittivity

We consider a system consisting of single electrons moving along a 1D wire in the presence of two magnetic impurities. Such system shows strong analogies with a Fabry - Perot interferometer in which the impurities play the role of two mirrors with a quantum degree of freedom: the spin. We have analysed the electron transmittivity of the wire in the presence of entanglement between the impurity spins. The main result of our analysis is that, for suitable values of the electron momentum, there are two maximally entangled state of the impurity spins the first of which makes the wire transparent whatever the electron spin state while the other strongly inhibits the electron transmittivity. Such predicted striking effect is experimentally observable with present day technology.Comment: Published version (6 figures

From Low-Distortion Norm Embeddings to Explicit Uncertainty Relations and Efficient Information Locking

The existence of quantum uncertainty relations is the essential reason that some classically impossible cryptographic primitives become possible when quantum communication is allowed. One direct operational manifestation of these uncertainty relations is a purely quantum effect referred to as information locking. A locking scheme can be viewed as a cryptographic protocol in which a uniformly random n-bit message is encoded in a quantum system using a classical key of size much smaller than n. Without the key, no measurement of this quantum state can extract more than a negligible amount of information about the message, in which case the message is said to be "locked". Furthermore, knowing the key, it is possible to recover, that is "unlock", the message. In this paper, we make the following contributions by exploiting a connection between uncertainty relations and low-distortion embeddings of L2 into L1. We introduce the notion of metric uncertainty relations and connect it to low-distortion embeddings of L2 into L1. A metric uncertainty relation also implies an entropic uncertainty relation. We prove that random bases satisfy uncertainty relations with a stronger definition and better parameters than previously known. Our proof is also considerably simpler than earlier proofs. We apply this result to show the existence of locking schemes with key size independent of the message length. We give efficient constructions of metric uncertainty relations. The bases defining these metric uncertainty relations are computable by quantum circuits of almost linear size. This leads to the first explicit construction of a strong information locking scheme. Moreover, we present a locking scheme that is close to being implementable with current technology. We apply our metric uncertainty relations to exhibit communication protocols that perform quantum equality testing.Comment: 60 pages, 5 figures. v4: published versio

Neutron star matter equation of state and gravitational wave emission

The EOS of strongly interacting matter at densities ten to fifteen orders of magnitude larger than the typical density of terrestrial macroscopic objects determines a number of neutron star properties, including the pattern of gravitational waves emitted following the excitation of nonradial oscillation modes. This paper reviews some of the approaches employed to model neutron star matter, as well as the prospects for obtaining new insights from the experimental study of gravitational waves emitted by neutron stars.Comment: 15 pages, 8 figures. To be published as a Brief Review in Modern Physics Letters