Geerligs, Peters, and Mooij reply:

Abstract

Geerligs, Peters, and Mooij Reply:The clear distinction between mutual and self-capacitance that Ferrell and Mirhashem l make is significant for quantitative comparison of our experiments with theories of phase transitions. In our Letter 2 the transition at x around 1 was quoted 3 as an approximate threshold. As such the distinction is less relevant since both choices of capacitance yield comparable results. In a mean-field approximation, e.g., Efetov finds for self-charging a critical x equal to l. 3 Doniach arrives, for mutual capacitance, at x=2. 3 Recently, Eckern and Schon performed a mean-field treatment for arbitrary mutual and self-capacitance. 4 They also find a critical x of order 1 for mutual capacitance much larger than self-capacitance.We agree that for a more reliable check of theory with experiments smaller junctions would be helpful but of course their fabrication is nontrivial. Among other present uncertainties are the effect of additional elements in the capacitance matrix, and the question of the appropriate "tunneling horizon" for the determination of C e ff. 5 This last item can make a difference of about a factor of 3 in the experimental determination of the junction capacitance.

Phase Glass is a Bose Metal: A New Conducting State in Two Dimensions

“…Further, the conductivity scales as 1/m 4 and hence diverges as the superconducting phase is approached. This is precisely what is seen experimentally [1][2][3][4]. That the conductivity plateaus in the phase glass regime does not appear to have been anticipated previously.…”

“…There is now a preponderance of experimental evidence [1][2][3][4] that the disorder or magnetic field-induced destruction of superconductivity in a wide range of thin metal alloy films leads first to a metallic state with a non-zero conductivity as T → 0. At sufficiently large values of the disorder or magnetic field, a transition to a true insulating state obtains.…”

“…To see how this comes about, we use the generalization [20] of the Kubo formula for the replicated action and write the conductivity to one-loop order per replica in the Gaussian approximation as σ(iω n ) = 2(e * ) 2 nhω n T a,b,ωm…”

Absence of Single-Particle Bose-Einstein Condensation at Low Densities for Bosons with Correlated Hopping

“…They are studied for a variety of reasons, coming from different experimental systems, such as Josephson junction arrays [1], 4 He in porous media [2], disordered films with superconducting and insulating phases [3], or more recently in the context of atoms trapped on an optical lattice [4]. The interplay of interaction, disorder and kinetic energy leads to the ground states that can be a superfluid, a Bose glass, a Mott insulator or a supersolid [5][6][7][8][9][10][11].…”

The Bose-Hubbard model: from Josephson junction arrays to optical lattices

“…Josephson junction arrays in the quantum regime were first fabricated in Delft [16]. It became possible to enter this regime due to the progress in lithography that allowed realizing submicron junctions with a high tunneling resistance (of the order of a few kΩ).…”