  Amplifiers are ubiquitous in electronics and play a fundamental role in a
wide range of scientific measurements. From a user's perspective, an ideal
amplifier has very low noise, operates over a broad frequency range, and has a
high dynamic range - it is capable of handling strong signals with little
distortion. Unfortunately, it is difficult to obtain all of these
characteristics simultaneously. For example, modern transistor amplifiers offer
multi-octave bandwidths and excellent dynamic range. However, their noise
remains far above the fundamental limit set by the uncertainty principle of
quantum mechanics. Parametric amplifiers, which predate transistor amplifiers
and are widely used in optics, exploit a nonlinear response to transfer power
from a strong pump tone to a weak signal. If the nonlinearity is purely
reactive, ie. nondissipative, in theory the amplifier noise can reach the
quantum-mechanical limit. Indeed, microwave frequency superconducting Josephson
parametric amplifiers do approach the quantum limit, but generally are narrow
band and have very limited dynamic range. In this paper, we describe a
superconducting parametric amplifier that overcomes these limitations. The
amplifier is very simple, consisting only of a patterned metal film on a
dielectric substrate, and relies on the nonlinear kinetic inductance of a
superconducting transmission line. We measure gain extending over 2 GHz on
either side of an 11.56 GHz pump tone, and we place an upper limit on the added
noise of the amplifier of 3.4 photons at 9.4 GHz. Furthermore, the dynamic
range is very large, comparable to microwave transistor amplifiers, and the
concept can be applied throughout the microwave, millimeter-wave and
submillimeter-wave bands.
