Connecting Berry's phase and the pumped charge in a Cooper pair pump

The properties of the tunnelling-charging Hamiltonian of a Cooper pair pump are well understood in the regime of weak and intermediate Josephson coupling, i.e. when $E_{\mathrm{J}}\lesssim E_{\mathrm{C}}$. It is also known that Berry's phase is related to the pumped charge induced by the adiabatical variation of the eigenstates. We show explicitly that pumped charge in Cooper pair pump can be understood as a partial derivative of Berry's phase with respect to the phase difference $\phi$ across the array. The phase fluctuations always present in real experiments can also be taken into account, although only approximately. Thus the measurement of the pumped current gives reliable, yet indirect, information on Berry's phase. As closing remarks, we give the differential relation between Berry's phase and the pumped charge, and state that the mathematical results are valid for any observable expressible as a partial derivative of the Hamiltonian.Comment: 5 pages, 5 figures, RevTeX, Presentation has been clarifie

Neoliberal growth models, monetary union and the Euro Crisis : a post-Keynesian perspective

The paper offers an account of the Euro crisis based on post-Keynesian monetary theory and its typology of demand regimes. Neoliberalism has transformed social and financial relations in Europe but it has not given rise to a sustained profit-led growth process. Instead, growth has relied either on financial bubbles and rising household debt (‘debt-driven growth’) or on net exports (‘export-driven growth’). In Europe the financial crisis has been amplified by an economic policy architecture (the Stability and Growth Pact) that aimed at restricting the role of fiscal policy and monetary policy. This neoliberal economic policy regime in conjunction with the separation of monetary and fiscal spheres has turned the financial crisis of 2007 into a sovereign debt crisis in southern Europe

Quantum information processing with superconducting qubits in a microwave field

We investigate the quantum dynamics of a Cooper-pair box with a superconducting loop in the presence of a nonclassical microwave field. We demonstrate the existence of Rabi oscillations for both single- and multi-photon processes and, moreover, we propose a new quantum computing scheme (including one-bit and conditional two-bit gates) based on Josephson qubits coupled through microwaves.Comment: 7 pages, 1 figur