In this paper we describe a new approach to the detection of human body electrical activity which has been made possible by recent advances in ultra-low-noise, ultra-high-input-impedance probes. As we demonstrate, these probes, which do not require a real current conducting path in order to operate, can be used non-invasively both on and off body. We present remarkable new data showing the application of these probes to the remote, off-body, sensing of the electrical activity of the heart at distances of up to 1 m from the body and to high-resolution electrocardiograms. We suggest that in the future such probes may form the basis of a radically new technology for measuring the dynamics of the human body as well as in non-contact, imaging systems for pre-emptive and diagnostic medicine.

In this paper we describe a new very-low-noise, high-input-impedance probe developed to make non-contact measurements of electrical potentials generated by currents flowing in the human body. With a noise level of 2 µV Hz-1/2 at 1 Hz, down to 0.1 µV Hz-1/2 at 1 kHz, and an operational bandwidth from 0.01 Hz to 100 KHz, this probe would seem well suited to the detection of a wide range of electrical activity in the body.

We consider the feasibility offabricating planar superconductor-semiconductor-superconductor Josephson junctions in which the junction supercurrent is controlled by a gate electrode isolated from the junction by either a dielectric film (MOS-JOFET) or a Schottky barrier (MES-JOFET). We fin~ that device critical currents between ~ 1 and 100 f-lA and critical temperatures approxImately a few K appear possible. We discuss the circuit applications of such devices.

A quantum system comprising of a monochromatic electromagnetic field coupled to a superconducting quantum interference device ͑SQUID͒ ring with sinusoidal nonlinearity is studied. A magnetostatic flux ⌽ x is also threading the SQUID ring, and is used to control the coupling between the two systems. It is shown that for special values of ⌽ x the system is strongly coupled. The time evolution of the system is studied. It is shown that exchange of energy takes place between the two modes and that the system becomes entangled. A second quasiclassical model that treats the electromagnetic field classically is also studied. A comparison between the fully quantum-mechanical model with the electromagnetic field initially in a coherent state and the quasiclassical model is made.