Testing quantum adiabaticity with quench echo

Adiabaticity of quantum evolution is important in many settings. One example is the adiabatic quantum computation. Nevertheless, up to now, there is no effective method to test the adiabaticity of the evolution when the eigenenergies of the driven Hamiltonian are not known. We propose a simple method to check adiabaticity of a quantum process for an arbitrary quantum system. We further propose a operational method for finding a uniformly adiabatic quench scheme based on Kibble-Zurek mechanism for the case when the initial and the final Hamiltonians are given. This method should help in implementing adiabatic quantum computation.Comment: This is a new version. Some typos in the New Journal of Physics version have been correcte

Mixed-state fidelity and quantum criticality at finite temperature

We extend to finite temperature the fidelity approach to quantum phase transitions (QPTs). This is done by resorting to the notion of mixed-state fidelity that allows one to compare two density matrices corresponding to two different thermal states. By exploiting the same concept we also propose a finite-temperature generalization of the Loschmidt echo. Explicit analytical expressions of these quantities are given for a class of quasi-free fermionic Hamiltonians. A numerical analysis is performed as well showing that the associated QPTs show their signatures in a finite range of temperatures.Comment: 7 pages, 4 figure

Molecular basis of retinol anti‐ageing properties in naturally aged human skin in vivo

ObjectiveRetinoic acid has been shown to improve the aged‐appearing skin. However, less is known about the anti‐ageing effects of retinol (ROL, vitamin A), a precursor of retinoic acid, in aged human skin in vivo. This study aimed to investigate the molecular basis of ROL anti‐ageing properties in naturally aged human skin in vivo.MethodsSun‐protected buttock skin (76 ± 6 years old, n = 12) was topically treated with 0.4% ROL and its vehicle for 7 days. The effects of topical ROL on skin epidermis and dermis were evaluated by immunohistochemistry, in situ hybridization, Northern analysis, real‐time RT‐PCR and Western analysis. Collagen fibrils nanoscale structure and surface topology were analysed by atomic force microscopy.ResultsTopical ROL shows remarkable anti‐ageing effects through three major types of skin cells: epidermal keratinocytes, dermal endothelial cells and fibroblasts. Topical ROL significantly increased epidermal thickness by stimulating keratinocytes proliferation and upregulation of c‐Jun transcription factor. In addition to epidermal changes, topical ROL significantly improved dermal extracellular matrix (ECM) microenvironment; increasing dermal vascularity by stimulating endothelial cells proliferation and ECM production (type I collagen, fibronectin and elastin) by activating dermal fibroblasts. Topical ROL also stimulates TGF‐β/CTGF pathway, the major regulator of ECM homeostasis, and thus enriched the deposition of ECM in aged human skin in vivo. 0.4% topical ROL achieved similar results as seen with topical retinoic acid, the biologically active form of ROL, without causing noticeable signs of retinoid side effects.Conclusion0.4% topical ROL shows remarkable anti‐ageing effects through improvement of the homeostasis of epidermis and dermis by stimulating the proliferation of keratinocytes and endothelial cells, and activating dermal fibroblasts. These data provide evidence that 0.4% topical ROL is a promising and safe treatment to improve the naturally aged human skin.RésuméObjectifL’acide rétinoïque a été montré améliorer l’apparence de la peau âgée. Cependant, on connaît moins les effets anti‐vieillissement de rétinol (ROL, de la vitamine A), un précurseur de l’acide rétinoïque, dans la peau humaine in vivo. Cette étude visait à étudier la base moléculaire des propriétés anti‐vieillissement du retinol de la peau humaine naturellement vieillie in vivo.MethodesLa peau des fesses protégée des UV (76 ± 6 ans, n = 12) a été traitée par voie topique avec 0,4% ROL et son véhicule pendant sept jours. Les effets du ROL topique sur l’épiderme et le derme de la peau ont été évalués par immunohistochimie, l’hybridation in situ, l’analyse Northern, RT‐PCR en temps réel, et analyse Western. La structure des fibrilles de collagène à l’échelle nanométrique et la topologie de surface ont été analysés par microscopie à force atomique.RésultatsROL par voie topique montre des effets anti‐âge remarquables à travers trois grands types de cellules de la peau: les kératinocytes épidermiques, les cellules endothéliales et les fibroblastes dermiques. ROL topique augmente de manière significative l’épaisseur de l’épiderme en stimulant la prolifération des kératinocytes et une régulation positive du facteur de transcription c‐Jun. En plus des changements de l’épiderme, le ROL topique améliore significativement le microenvironnement de la matrice extracellulaire (ECM) dermique: augmentation de la vascularisation cutanée par stimulation de la prolifération des cellules endothéliales et la production d’ECM (collagène de type I, la fibronectine et l’élastine), en activant les fibroblastes dermiques. Le ROL topique stimule également la voie TGF‐β / CTGF, le principal régulateur de l’homéostasie ECM, et donc enrichit le dépôt d’ECM dans la peau âgée humaine in vivo. L’application topique de 0,4% ROL obtient des résultats similaires à ceux observés avec l’acide rétinoïque topique, la forme biologiquement active de ROL, sans provoquer de signes apparents d’effets secondaires associés aux rétinoïdes.ConclusionL’application topique de 0,4% ROL montre des effets remarquables anti‐âge grâce à une amélioration de l’homéostasie du derme et l’épiderme, en stimulant la prolifération des kératinocytes et des cellules endothéliales, et l’activation des fibroblastes dermiques. Ces données fournissent la preuve que l’application topique de 0,4% ROL est un traitement prometteur et sûr pour améliorer la peau humaine vieillie naturellement.Topical application of 0.4% ROL to aged human skin leads to remarkable skin changes in both epidermis and dermis through affecting three major types of skin cells, epidermal keratinocytes, dermal endothelial cells and fibroblasts.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/136029/1/ics12348.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/136029/2/ics12348_am.pd

Sensitive Chemical Compass Assisted by Quantum Criticality

The radical-pair-based chemical reaction could be used by birds for the navigation via the geomagnetic direction. An inherent physical mechanism is that the quantum coherent transition from a singlet state to triplet states of the radical pair could response to the weak magnetic field and be sensitive to the direction of such a field and then results in different photopigments in the avian eyes to be sensed. Here, we propose a quantum bionic setup for the ultra-sensitive probe of a weak magnetic field based on the quantum phase transition of the environments of the two electrons in the radical pair. We prove that the yield of the chemical products via the recombination from the singlet state is determined by the Loschmidt echo of the environments with interacting nuclear spins. Thus quantum criticality of environments could enhance the sensitivity of the detection of the weak magnetic field.Comment: 4 pages, 3 figure

Quantum secure communication scheme with W state

Recently, Cao et al. proposed a new quantum secure direct communication scheme using W state. In their scheme, the error rate introduced by an eavesdropper who takes intercept-resend attack, is only 8.3%. Actually, their scheme is just a quantum key distribution scheme because the communication parties first create a shared key and then encrypt the secret message using one-time pad. We then present a quantum secure communication scheme using three-qubit W state. In our scheme, the error rate is raised to 25% and it is not necessary for the present scheme to use alternative measurement or Bell basis measurement. We also show our scheme is unconditionally secure.Comment: Comments are welcom

Quenched Charmed Meson Spectra using Tadpole Improved Quark Action on Anisotropic Lattices

Charmed meson charmonium spectra are studied with improved quark actions on anisotropic lattices. We measured the pseudo-scalar and vector meson dispersion relations for 4 lowest lattice momentum modes with quark mass values ranging from the strange quark to charm quark with 3 different values of gauge coupling $\beta$ and 4 different values of bare speed of light $\nu$. With the bare speed of light parameter $\nu$ tuned in a mass-dependent way, we study the mass spectra of $D$, $D_s$, $\eta_c$, $D^{\ast}$, $D_s^{\ast}$ and $J/\psi$ mesons. The results extrapolated to the continuum limit are compared with the experiment and qualitative agreement is found.Comment: 8 pages, 2 figures, latex fil

Multiparty simultaneous quantum identity authentication based on entanglement swapping

We present a multiparty simultaneous quantum identity authentication protocol based on entanglement swapping. In our protocol, the multi-user can be authenticated by a trusted third party simultaneously

Quantum Critical Dynamics of A Qubit Coupled to An Isotropic Lipkin-Meshkov-Glick Bath

We explore a dynamic signature of quantum phase transition (QPT) in an isotropic Lipkin-Meshkov-Glick (LMG) model by studying the time evolution of a central qubit coupled to it. We evaluate exactly the time-dependent purity, which can be used to measure quantum coherence, of the central qubit. It is found that distinctly different behaviors of the purity as a function of the parameter reveal clearly the QPT point in the system. It is also clarified that the present model is equivalent to an anti Jaynes-Cummings model under certain conditions.Comment: 8 pages, 4 figure

Pseudospin symmetry and its approximation in real nuclei

The origin of pseudospin symmetry and its broken in real nuclei are discussed in the relativistic mean field theory. In the exact pseudospin symmetry, even the usual intruder orbits have degenerate partners. In real nuclei, pseudospin symmetry is approximate, and the partners of the usual intruder orbits will disappear. The difference is mainly due to the pseudo spin-orbit potential and the transition between them is discussed in details. The contribution of pseudospin-orbit potential for intruder orbits is quite large, compared with that for pseudospin doublets. The disappearance of the pseudospin partner for the intruder orbit can be understood from the properties of its wave function.Comment: 10 pages, 3 figure