Arrays of Josephson tunnel junctions as parametric amplifiers

Abstract

Arrays of 10 or 40 series-connected small densely packed Josephson tunnel junctions were successfully operated as parametric amplifiers at 10 GHz. Between 50 and 90% of the junctions in an array were observed to work coherently in the amplification process. Signal gain exceeding 24 dB was achieved with a pump power as low as -50 to -70 dBm. A power width (i.e., the range of the pump power for a gain within 3 dB of the peak gain) of 0.25 dB and a bandwidth of IS MHz were measured for 20-dB gain. The power width was in accordance with theory but the bandwidth was reduced, probably due to noise saturation effects. The latter effects can be reduced by lowering the input noise temperature or by including an external band limitation. The noise temperature was also increased by saturation; however, with an external bandwidth of 60 MHz, a noise temperature of 30 ± 20 K was measured. The application of a magnetic field has proved extremely useful as a means of tuning the amplifiers to stable high-gain operating points. This tuning was also utilized in evaluating the amplifier parameters, and the theory by Feldman, Parrish, and Chiao has been verified. The upper frequency limit for a lead tunnel junction amplifier ought to be well above 300 GHz.

Escape Time of Josephson Junctions for Signal Detection

“…The phenomenon is associated with a multivalued resonance curve of the non linear plasma frequency [37]. It is remarkable, to our opinion, that best detection performances (in terms of error probability P e ) are reached in the same strongly non linear distortion regime as in amplifiers [58]. Focusing on the coherent case, we note that for SM strategy a second interesting region occurs at a lower normalized signal frequency x SR (see ðbÞ in Fig.…”

Wireless Josephson amplifier

“…We present an experimental realization of such a device operating in the 9 − 11 GHz band with about 100 MHz of amplitude gain-bandwidth product, on par with devices mounted in conventional sample holders. The simpler impedance environment presented to the amplifier also results in increased amplifier tunability.Parametric amplifiers (paramps) based on Josephson junctions [1][2][3], such as the Josephson Bifurcation Amplifier (JBA) and its degenerate amplifier relatives [4][5][6][7][8][9][10][11][12][13] and the Josephson Parametric Converter (JPC) [14][15][16][17][18][19], have become essential components in the quantum non-demolition (QND) readout chain of superconducting qubits. They have been instrumental in the experimental observation of quantum jumps [20], the detailed study of the quantum backaction of measurement [21,22], and feedback [23,24], and will remain essential in future experiments aimed at quantum error correction and beyond [25,26].…”

Superconductive devices for millimeter wave detection, mixing, and amplification

“…This hope has not been realized because of the appearance of an unexpected noise phenomenon which is often referred to as the "noise rise." The dominant contribution to the amplifier noise temperature is observed to be proportional to its gain [52,53,56,57]. It has recently been suggested that phase instability will be amplified in this way [55].…”