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Probing the Scale Invariance of the Inflationary Power Spectrum in Expanding Quasi-Two-Dimensional Dipolar Condensates

Author(s): Seok-Yeong Chä and Uwe R. Fischer
We consider an analogue de Sitter cosmos in an expanding quasi-two-dimensional Bose-Einstein condensate with dominant dipole-dipole interactions between the atoms or molecules in the ultracold gas. It is demonstrated that a hallmark signature of inflationary cosmology, the scale invariance of the po…
[Phys. Rev. Lett. 118, 130404] Published Thu Mar 30, 2017

Quantum noise generated by local random Hamiltonians

Author(s): Marcin Markiewicz, Zbigniew Puchała, Anna de Rosier, Wiesław Laskowski, and Karol Życzkowski
We investigate the impact of a local random unitary noise on multipartite quantum states of an arbitrary dimension. We follow the dynamical approach, in which the single-particle unitaries are generated by local random Hamiltonians. Assuming short evolution time we derive a lower bound on the fideli…
[Phys. Rev. A 95, 032333] Published Thu Mar 30, 2017

Experimental quantum digital signature over 102 km

Author(s): Hua-Lei Yin, Yao Fu, Hui Liu, Qi-Jie Tang, Jian Wang, Li-Xing You, Wei-Jun Zhang, Si-Jing Chen, Zhen Wang, Qiang Zhang, Teng-Yun Chen, Zeng-Bing Chen, and Jian-Wei Pan
Quantum digital signature (QDS) is an approach to guarantee the nonrepudiation, unforgeability, and transferability of a signature with information-theoretical security. Previous experimental realizations of QDS relied on an unrealistic assumption of secure channels and the longest distance is sever…
[Phys. Rev. A 95, 032334] Published Thu Mar 30, 2017

Necessary adiabatic run times in quantum optimization

Author(s): Lucas T. Brady and Wim van Dam
Quantum annealing is guaranteed to find the ground state of optimization problems provided it operates in the adiabatic limit. Recent work [S. Muthukrishnan et al., Phys. Rev. X 6, 031010 (2016)] has found that for some barrier tunneling problems, quantum annealing can be run much faster than is ad…
[Phys. Rev. A 95, 032335] Published Thu Mar 30, 2017

Scheme for coherent-state quantum process tomography via normally-ordered moments

Author(s): M. Ghalaii and A. T. Rezakhani
Using coherent states in optical quantum process tomography is a practically relevant approach. Here we develop a framework for complete characterization of quantum-optical processes in terms of normally-ordered moments by using coherent states as probes. We derive the associated superoperator tenso…
[Phys. Rev. A 95, 032336] Published Thu Mar 30, 2017

Experimental Adiabatic Quantum Factorization under Ambient Conditions Based on a Solid-State Single Spin System

Author(s): Kebiao Xu, Tianyu Xie, Zhaokai Li, Xiangkun Xu, Mengqi Wang, Xiangyu Ye, Fei Kong, Jianpei Geng, Changkui Duan, Fazhan Shi, and Jiangfeng Du
The adiabatic quantum computation is a universal and robust method of quantum computing. In this architecture, the problem can be solved by adiabatically evolving the quantum processor from the ground state of a simple initial Hamiltonian to that of a final one, which encodes the solution of the pro…
[Phys. Rev. Lett. 118, 130504] Published Thu Mar 30, 2017

Many-Particle Dephasing after a Quench

Author(s): Thomas Kiendl and Florian Marquardt
After a quench in a quantum many-body system, expectation values tend to relax towards long-time averages. However, temporal fluctuations remain in the long-time limit, and it is crucial to study the suppression of these fluctuations with increasing system size. The particularly important case of no…
[Phys. Rev. Lett. 118, 130601] Published Thu Mar 30, 2017

Hamiltonian for the Zeros of the Riemann Zeta Function

Author(s): Carl M. Bender, Dorje C. Brody, and Markus P. Müller
A Hamilonian with PT-symmetry invariant properties is investigated as a candidate for an operator that has eigenvalues corresponding to the nontrivial zeros of the Riemann zeta function.
[Phys. Rev. Lett. 118, 130201] Published Thu Mar 30, 2017

A generalized quantum Slepian-Wolf. (arXiv:1703.09961v1 [quant-ph])

In this work we consider a quantum generalization of the task considered by
Slepian and Wolf [1973] regarding distributed source compression. In our task
Alice, Bob, Charlie and Referee share a joint pure state. Alice and Bob wish to
send a part of their respective systems to Charlie without collaborating with
each other. We give achievability bounds for this task in the one-shot setting
and provide asymptotic analysis in the case when there is no side information
with Charlie.

Quantum walks and gravitational waves. (arXiv:1609.00722v2 [quant-ph] UPDATED)

A new family of discrete-time quantum walks (DTQWs) propagating on a regular
$(1+2)$D spacetime lattice is introduced. The continuous limit of these DTQWs
is shown to coincide with the dynamics of a Dirac fermion interacting with an
arbitrary relativistic gravitational field. This family is used to model the
influence of arbitrary linear gravitational waves (GWs) on DTQWs. Pure shear
GWs are studied in detail. On large spatial scales, pure shear GWs do not