DSpace Collection:https://dspace.lboro.ac.uk/2134/11342018-03-09T18:24:38Z2018-03-09T18:24:38ZPressure induced changes in the antiferromagnetic superconductor YbPd2SnCumberlidge, A.-M.Alireza, P.L.Kusmartseva, Anna F.Pearson, E.E.Lonzarich, G.G.Bernhoeft, N.R.Roessli, B.https://dspace.lboro.ac.uk/2134/275202017-11-20T16:31:36Z2006-05-17T00:00:00ZTitle: Pressure induced changes in the antiferromagnetic superconductor YbPd2Sn
Authors: Cumberlidge, A.-M.; Alireza, P.L.; Kusmartseva, Anna F.; Pearson, E.E.; Lonzarich, G.G.; Bernhoeft, N.R.; Roessli, B.
Abstract: Low temperature ac magnetic susceptibility measurements of the coexistent antiferromagnetic superconductor YbPd2Sn have been made in hydrostatic pressures < 74 kbar in moissanite anvil cells. The superconducting transition temperature is forced to T(SC) = 0 K at a pressure of 58 kbar. The initial suppression of the superconducting transition temperature is corroborated by lower hydrostatic pressure (p < 16 kbar) four point resisitivity measurements, made in a piston cylinder pressure cell. At ambient pressure, in a modest magnetic field of ~ 500 G, this compound displays reentrant superconducting behaviour. This reentrant superconductivity is suppressed to lower temperature and lower magnetic field as pressure is increased. The antiferromagnetic ordering temperature, which was measured at T(N) = 0.12 K at ambient pressure is enhanced, to reach T(N) = 0.58 K at p = 74 kbar. The reasons for the coexistence of superconductivity and antiferromagnetism is discussed in the light of these and previous findings. Also considered is why superconductivity on the border of long range magnetic order is so much rarer in Yb compounds than in Ce compounds. The presence of a new transition visible by ac magnetic susceptibility under pressure and in magnetic fields greater than 1.5 kG is suggested.
Description: This is an ArXiv pre-print. It is also available online at: https://arxiv.org/abs/cond-mat/06054292006-05-17T00:00:00ZQuasi-superradiant soliton state of matter in quantum metamaterialsAsai, HidehiroKawabata, ShiroZagoskin, Alexandre M.Savel'ev, Sergeyhttps://dspace.lboro.ac.uk/2134/217282016-06-20T15:29:16Z2016-01-01T00:00:00ZTitle: Quasi-superradiant soliton state of matter in quantum metamaterials
Authors: Asai, Hidehiro; Kawabata, Shiro; Zagoskin, Alexandre M.; Savel'ev, Sergey
Abstract: Strong interaction of a system of quantum emitters (e.g., two-level atoms) with electromagnetic field induces specific correlations in the system accompanied by a drastic insrease of emitted radiation (superradiation or superfluorescence). Despite the fact that since its prediction this phenomenon was subject to a vigorous experimental and theoretical research, there remain open question, in particular, concerning the possibility of a first order phase transition to the superradiant state from the vacuum state. In systems of natural and charge-based artificial atome this transition is prohibited by "no-go" theorems. Here we demonstrate numerically a similar transition in a one-dimensional quantum metamaterial - a chain of artificial atoms (qubits) strongly interacting with classical electromagnetic fields in a transmission line. The system switches from vacuum state with zero classical electromagnetic fields and all qubits being in the ground state to the quasi-superradiant (QS) phase with one or several magnetic solitons and finite average occupation of qubit excited states along the transmission line. A quantum metamaterial in the QS phase circumvents the "no-go" restrictions by considerably decreasing its total energy relative to the vacuum state by exciting nonlinear electromagnetic solitons with many nonlinearly coupled electromagnetic modes in the presence of external magnetic field.
Description: This is a pre-print.2016-01-01T00:00:00ZCool for catsEveritt, Mark J.Spiller, T.P.Milburn, G.J.Wilson, Richard D.Zagoskin, Alexandre M.https://dspace.lboro.ac.uk/2134/212922016-05-20T10:20:31Z2012-01-01T00:00:00ZTitle: Cool for cats
Authors: Everitt, Mark J.; Spiller, T.P.; Milburn, G.J.; Wilson, Richard D.; Zagoskin, Alexandre M.
Abstract: The iconic SchrÃ¶dinger's cat state describes a system that may be in a superposition of two macroscopically distinct states, for example two clearly separated oscillator coherent states. Quite apart from their role in understanding the quantum classical boundary, such states have been suggested as offering a quantum advantage for quantum metrology, quantum communication and quantum computation. As is well known these applications have to face the difficulty that the irreversible interaction with an environment causes the superposition to rapidly evolve to a mixture of the component states in the case that the environment is not monitored. Here we show that by engineering the interaction with the environment there exists a large class of systems that can evolve irreversibly to a cat state. To be precise we show that it is possible to engineer an irreversible process so that the steady state is close to a pure Schr\"odinger's cat state by using double well systems and an environment comprising two-photon (or phonon) absorbers. We also show that it should be possible to prolong the lifetime of a Schr\"odinger's cat state exposed to the destructive effects of a conventional single-photon decohering environment. Our protocol should make it easier to prepare and maintain Schr\"odinger cat states which would be useful in applications of quantum metrology and information processing as well as being of interest to those probing the quantum to classical transition.
Description: This pre-print was submitted to arXiv on 27 Feb 2013. It was subsequently published as "Engineering dissipative channels for realizing SchrÃ¶dinger cats in SQUIDs" https://dspace.lboro.ac.uk/2134/212962012-01-01T00:00:00ZNeural wave interference in inhibition-stabilized networksSavel'ev, SergeyGepshtein, Sergeihttps://dspace.lboro.ac.uk/2134/185322015-08-20T11:37:45Z2014-01-01T00:00:00ZTitle: Neural wave interference in inhibition-stabilized networks
Authors: Savel'ev, Sergey; Gepshtein, Sergei
Abstract: We study how excitation propagates in chains of inhibition-stabilized neural networks with nearest-neighbor coupling. The excitation generated by local stimuli in such networks propagates across space and time, forming spatiotemporal waves that affect the dynamics of excitation generated by stimuli separated spatially and temporally. These interactions form characteristic interference patterns, manifested as network preferences: for spatial and temporal frequencies of stimulus intensity, for stimulus velocities, and as contextual ("lateral") interactions between stimuli. Such preferences have been previously attributed to distinct specialized mechanisms.
Description: This paper is an extended version of the manuscript submitted to Entropy on October 10, 2014. It is also available from arXiv at: http://arxiv.org/abs/1410.4237v12014-01-01T00:00:00Z