Thermally pumped on-chip maser

Abstract

We present a theoretical model of an on-chip three-level maser in a superconducting circuit based on a single artificial atom and pumped by a temperature gradient between thermal baths coupled to different interlevel transitions. We show that maser powers of the order of a few femtowatts, well exceeding the resolution of the sensitive bolometry, can be achieved with typical circuit parameters. We also demonstrate that population inversion in the artificial atom can be detected without measuring coherent radiation output of the maser. For that purpose, the system should operate as a three-terminal heat transport device. The hallmark of population inversion is the influx of heat power into the weakly coupled output terminal even though its temperature exceeds the temperatures of the two other terminals. The proposed method of on-chip conversion of heat into microwave radiation and control of energy-level populations by heating provide additional useful tools for circuit quantum electrodynamics experiments.

Quantum thermodynamic devices: from theoretical proposals to experimental reality

“…Thus, the maser is a simple and pedagogically valuable system to study the whole range of thermodynamic devices. Remarkably, this three level system is, however, not only a toy model, but actually a good description of experimentally realistic masers 17,19,20 .…”

The qutrit as a heat diode and circulator

“…Let us from now on consider the system to be realized by a superconducting qutrit, following the proposal in reference [82], as represented in figure 1(c). The qutrit is defined by a superconducting island connected via the two arms of a loop to the superconducting ground.…”

“…For more detailed discussions in terms of the experimental setup parameters, see references [82,84]. With these rates, we are ready to write the master equation ( 2) and obtain the dissipated heat currents using equation (3).…”

“…This is indeed the case in most experiments, due to the finite width of the resonator spectral functions. Furthermore this is, up to some extent, a desirable property for practical reasons in the lab: very narrow resonances are difficult to match to the system frequencies [82]. We consider a simple configuration consisting on a qutrit coupled to three thermal baths via three finite quality-factor resonators, see figure 1(c).…”

Photonic heat transport in three terminal superconducting circuit

“…However, according to the theory, moving to three terminal setup [13] should open up new opportunities. Indeed, there exist theory proposals for thermal transistors [14][15][16][17], heat amplifiers [18,19], quantum absorption refrigerators [20,21] and thermally pumped masers [22,23], which are heat engines from thermodynamical point of view, in this configuration. Motivated by these ideas, we have fabricated a three terminal heat transport device containing an Xmon qubit, which acts as a tunable element and controls photonic heat currents between the terminals.…”