Under certain circumstances, systems of quantum bosons can exhibit both rigid lattice structures (solidity) and at the same time resistanceless flow (superfluidity). This remarkable phase is known as a supersolid.
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R.T. Scalettar, G.G. Batrouni, A.P. Kampf, and G.T. Zimanyi,
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G.G. Batrouni and R.T. Scalettar,
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