Journal club

superflow T (K) 4 He Ns – Ss Cuprates Nc – PG – Sc Pressure (bar)Doping (h per CuO 2 ) Ns Ss Nc PG Sc

Cuprates (Bi 2 Sr 2 CaCu 2 O 8 ) Nc – PG – Sc Y. Wang, L. Li and N.P. Ong Phys. Rev. B, 73, (2006) T V T (K) Nernst signal Strong pair amplitude No supercurrent Strong phase fluct’s Vortex liquid PG (above T c ): T (K) 0 -B

Cuprates (Bi 2 Sr 2 CaCu 2 O 8 ) Nc – PG – Sc L. Li, Y. Wang, M.J. Naughton, S. Ono,Y. Ando and N.P. Ong, Europhys. Lett.,72, 451 (2005) Vortex liquid T (K)  Nonlinear susceptibility Incompressible Vortex liquid

4 He Ns – Ss O. Penrose and L. Onsager, Phys. Rev. 104, (1956): “…one would not expect B.E. condensation in a solid …” A.F. Andreev and I.M. Lifshitz Sov.Phys.JETP 29,1107–1113 (1969): “Quantum theory of defects in crystals” G. V. Chester, Phys. Rev. A 2, (1970): “…interacting bosons … exhibit both crystalline order and B.E. condensation…” “…if there are vacancies…then a condensate exists…” A.J. Leggett, Phys. Rev. Lett. 25, (1970): ”Nonclassical Rotational Inertia” K A,A, T (K)

4 He Ns – Ss E. Kim and M.H.W. Chan, Nature 427, 225 (2004) K Nonlinear susceptibility No direct observation of superflow A,A, T (K) 

4 He Ns–”PG”–Ss Cuprates Nc – PG – Sc Nonlinear  B No supercurrents PG – Incompressible Vortex Liquid   Strong pair amplitude + Strong phase fluctuations T (K) Nonlinear   No supercurrents found Ns “PG” SS

4 HeCuprates Fermionic Charged Bosonic Neutral Bosonic PG  Vortex liquid Fermionic PG superflow The end