论文标题
两波段超丝体的跨界和量子相变：通过调谐相互作用和带偏移从BCS到BOSE配对的演变
Crossovers and quantum phase transitions in two-band superfluids: The evolution from BCS to Bose pairing by tuning interactions and band offset
论文作者
论文摘要
We show that in two-band $s$-wave superfluids it is possible to induce quantum phase transitions (QPTs) by tuning intraband and interband $s$-wave interactions, in sharp contrast to single-band $s$-wave superfluids, where only a crossover between Bardeen-Cooper-Schrieffer (BCS) and Bose-Einstein condensation (BEC) superfluidity occurs. For non-zero interband and attractive intraband interactions, we demonstrate that the ground state has always two interpenetrating superfluids possessing three spectroscopically distinct regions where pairing is qualitatively different: (I) BCS pairing in both bands (BCS-BCS), (II) BCS pairing in one band and BEC pairing in the other (BCS-BEC), and (III) Bose pairing in both bands （BEC-BEC）。此外，我们表明，通过微调带之间的相互作用到零可以诱导三个不同的超氟相位之间的基态QPT。在两个阶段中，只有一个频段是超级流体（$ s_1 $或$ s_2 $），一个阶段，两个频段均为superfluid $（s_1 + s_2）$，这种情况在一条$ s $ s $ wave Systems中不存在。最后，我们建议可以在$^{173} $ yb和$^{87} $ sr中观察到这些交叉和QPT。
We show that in two-band $s$-wave superfluids it is possible to induce quantum phase transitions (QPTs) by tuning intraband and interband $s$-wave interactions, in sharp contrast to single-band $s$-wave superfluids, where only a crossover between Bardeen-Cooper-Schrieffer (BCS) and Bose-Einstein condensation (BEC) superfluidity occurs. For non-zero interband and attractive intraband interactions, we demonstrate that the ground state has always two interpenetrating superfluids possessing three spectroscopically distinct regions where pairing is qualitatively different: (I) BCS pairing in both bands (BCS-BCS), (II) BCS pairing in one band and BEC pairing in the other (BCS-BEC), and (III) Bose pairing in both bands (BEC-BEC). Furthermore, we show that by fine tuning the interband interactions to zero one can induce QPTs in the ground state between three distinct superfluid phases. There are two phases where only one band is superfluid ($S_1$ or $S_2$), and one phase where both bands are superfluid $(S_1 + S_2)$, a situation which is absent in one-band $s$-wave systems. Lastly, we suggest that these crossovers and QPTs may be observed in $^{173}$Yb and $^{87}$Sr.
