Scientists have Reversed the Arrow of Time in a Quantum Experiment in which they made two quantum correlated system to behave in an Unusual way during which the Second law of Thermodynamics failed. This experiment involved a quantum system of correlated spins to create the effect which proves the reversibility of the arrow of time.
However the Second Law of Thermodynamics holds firmly for every large scale Systems we Observe.
With over more than a couple of Centuries work, Arrow of time( or Irreversibility of Certain Processes ) still remained one of the greatest puzzle in physics. In the quantum world where microscopic laws of motion are invariant under time reversal, all macroscopic phenomena have a singular preference in time I.e, they have a definite direction in Time. Heat, Entropy etc. are some of the phenomenon included. Heat, for instance, spontaneously flows from hot to cold. One of the Greatest Scientist of 20th Century, Sir Arthur Stanley Eddington has called this asymmetry, The Arrow of Time. Talking at the simplest level, we all lear'nt in schools that the second law of thermodynamics allows one to predict which processes are possible in nature: only those with non-negative mean entropy production do occur. A microscopic resolution of the apparent paradox of irreversibility was put forward by Ludwig Boltzmann, when he noted that initial conditions break the time-reversal symmetry of the otherwise reversible dynamics . Quantitative experimental confirmation of this conjecture has recently been obtained for a driven classical Brownian particle and for an electrical RC circuit , as well as for a driven quantum spin , and a driven quantum dot .
In addition to breaking time reversal, initial conditions also determine the arrow’s direction. The observation ofthe average positivity of the entropy production in nature is often explained by the low entropy value of the initial state. This merely creates the possibility to reverse the arrow of time and control it effectively depending on the initial conditions of the experiment. In standard thermodynamics, systems are assumed to be uncorrelated before thermal contact. As aresult, according to the second law heat will flow from the hot to the cold body. However, it has been theoretically suggested that for quantum correlated local thermal states, heat might flow from the cold to the hot system,thus effectively reversing the arrow’s direction.
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"The second law permits the prediction of the direction of natural processes, thus defining a thermodynamic arrow of time. However, standard thermodynamics presupposes the absence of initial correlations between interacting systems. We here experimentally demonstrate the reversal
of the arrow of time for two initially quantum correlated spins-1/2, prepared in local thermal states at different temperatures, employing a Nuclear Magnetic Resonance setup. We observe a spontaneous heat flow from the cold to the hot system. This process is enabled by a trade off between correlations
and entropy that we quantify with information-theoretical quantities" said the Researchers in the Research Journal (ar.Xiv:1711.03323v1 quant ph ) Published on November 10.
The Scientists involed in this Experiment were :
Kaonan Micadei and Roberto M. Serra of Centro de Ciências Naturais e Humanas, Universidade Federal do ABC.
John P. S. Peterson, Alexandre M. Souza, Roberto S. Sarthour and Ivan S. Oliveira of Centro Brasileiro de Pesquisas Físicas.
Gabriel T. Landi of Instituto de Física, Universidade de São Paulo.
Tiago B. Batalhão of Singapore University of Technology and Design & Centre for Quantum Technologies, National University of Singapore, and Eric Lutz of Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany.
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