PMID- 26277127
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20151023
LR  - 20150817
IS  - 1089-7690 (Electronic)
IS  - 0021-9606 (Linking)
VI  - 143
IP  - 6
DP  - 2015 Aug 14
TI  - Quantum heat transport of a two-qubit system: Interplay between system-bath 
      coherence and qubit-qubit coherence.
PG  - 064107
LID - 10.1063/1.4928192 [doi]
AB  - We consider a system consisting of two interacting qubits that are individually 
      coupled to separate heat baths at different temperatures. The quantum effects in 
      heat transport are investigated in a numerically rigorous manner with a 
      hierarchial equations of motion (HEOM) approach for non-perturbative and 
      non-Markovian system-bath coupling cases under non-equilibrium steady-state 
      conditions. For a weak interqubit interaction, the total system is regarded as 
      two individually thermostatted systems, whereas for a strong interqubit 
      interaction, the two-qubit system is regarded as a single system coupled to two 
      baths. The roles of quantum coherence (or entanglement) between the two qubits 
      (q-q coherence) and between the qubit and bath (q-b coherence) are studied 
      through the heat current calculated for various strengths of the system-bath 
      coupling and interqubit coupling for high and low temperatures. The same current 
      is also studied using the time convolutionless (TCL) Redfield equation and using 
      an expression derived from the Fermi golden rule (FGR). We find that the HEOM 
      results exhibit turnover behavior of the heat current as a function of the 
      system-bath coupling strength for all values of the interqubit coupling strength, 
      while the results obtained with the TCL and FGR approaches do not exhibit such 
      behavior, because they do not possess the capability of treating the q-b and q-q 
      coherences. The maximum current is obtained in the case that the q-q coherence 
      and q-b coherence are balanced in such a manner that coherence of the entire heat 
      transport process is realized. We also find that the heat current does not follow 
      Fourier's law when the temperature difference is very large, due to the 
      non-perturbative system-bath interactions.
FAU - Kato, Akihito
AU  - Kato A
AD  - Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 
      606-8502, Japan.
FAU - Tanimura, Yoshitaka
AU  - Tanimura Y
AD  - Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 
      606-8502, Japan.
LA  - eng
PT  - Journal Article
PL  - United States
TA  - J Chem Phys
JT  - The Journal of chemical physics
JID - 0375360
EDAT- 2015/08/19 06:00
MHDA- 2015/08/19 06:01
CRDT- 2015/08/17 06:00
PHST- 2015/08/17 06:00 [entrez]
PHST- 2015/08/19 06:00 [pubmed]
PHST- 2015/08/19 06:01 [medline]
AID - 10.1063/1.4928192 [doi]
PST - ppublish
SO  - J Chem Phys. 2015 Aug 14;143(6):064107. doi: 10.1063/1.4928192.