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Scientists Verify Thermodynamics of Information at a Single Spin Level

Jan 12, 2018     Email"> PrintText Size

Being ubiquitous in dynamic evolutions, the nonequilibrium dynamic process is extremely complicated, which can be described only by inequalities.

C. Jarzynski proposed a simple and general equality in 1997 to connect the physical quantities in the nonequilibrium process to the free-energy change of the system. This equality was further generalized by V. Vedral for the change of information between two different measurements during the time evolution. The new equality, which is more suitable for quantum domain, can be reduced to the Jarzynski equation when the system is initially in a Gibbs state.

In a study published in Physical Review Letters, Prof. FENG Mang's group at Wuhan Institute of Physics and Mathematics of Chinese Academy of Sciences, together with the researchers from Shanghai Jiaotong University and Oxford University, firstly verified nonequilibrium thermodynamics of information at a single-spin level.

In previous studies, Prof. FENG’s group has achieved stable confinement of ultracold ions in an electromagnetic potential well and precise manipulation of quantum states of the ions, including arbitrary quantum-state preparation, laser-controlled quantum-state time evolution, laser-phase modulation and arbitrary projection measurement.

After considering the feasibility of single-qubit implementation for the information-theoretic equalities, they designed the experimental scheme, and carried out the experiment at the level of 0.7% error of single-spin operations under the influence of quantum and classical noises.

This study showed that the information-theoretic equalities, including the Jarzynski equality, work nearly perfectly at the fundamental level of a single spin. It will help to understand the thermodynamic behavior at quantum mechanical level and to explore new physics in quantum world from the viewpoint of quantum information.

The study was supported by National Key Research and Development Program of China, the Strategic Research Program of the Chinese Academy of Sciences and National Natural Science Foundation of China.


Experimental schematic (Image by FENG’s group) 


(Editor: LIU Jia)

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