JCJC SIMI 4 - JCJC - SIMI 4 - Physique des milieux condensés et dilués

Thermodynamics of Quantum Information with Superconducting Circuits – TIQS

Submission summary

We propose to realize a series of experiments investigating the thermodynamics of quantum information using superconducting circuits.

Since the introduction of the Maxwell’s demon in 1867, many physicists like Szilard, Landauer, Bennett and Feynman questioned the thermodynamics of systems with an internal memory, which lead to the advent of thermodynamics of information. A single experiment by Toyabe and coworkers in 2010 allowed to test some of its fundamental predictions. We propose here to realize experiments on superconducting circuits to test, for the first time, ideas of thermodynamics of information on systems made of a few quanta only. This experimental program can be seen as the realization of a Maxwell’s demon in a quantum system.

Experimental techniques:
We will work in the microwave domain with signal frequencies of a few GHz and base temperatures T<<hf/k ~500mK, allowing to control the thermal noise in dissipative components constituting the circuit environment. Our project will combine dilution refrigeration techniques, ultra-low noise microwave spectral measurements, fast feedback, and nanofabrication of superconducting circuits by e-beam lithography.<br />
State of the art:
Several groups are developing the theory of thermodynamics of quantum information but no other experiments are being performed on this subject to our knowledge. Our assets are a deep knowledge of the physics of mesoscopic superconducting circuits, microwave engineering, fabrication and control of circuits with tunnel junctions, which are the model system for this research.

Experimental program:
The first experiment consists in making and operating a circuit allowing to manipulate the entropy flow between two microwave channels in a controlled way. We will for instance be able to cool down a field close to the vacuum state even in presence of thermal excitations due to a warm environment (kT>hf). The circuit will use a network of Josephson junctions, superconducting inductances, and capacitances in order to realize an efficient parametric converter between channels with a well suited bandwidth.

In the second experiment, we will cool down a superconducting qubit close to its ground state using two strategies. First by using measurement feedback, which can be viewed as a macroscopic Maxwell demon. Then by using the above circuit in order to cool down the electromagnetic field seen by the qubit. This experiment will therefore improve the preparation of qubit states in a future quantum computer.

Finally, we will realize an actual quantum Maxwell’s demon using two superconducting qubits with tunable coupling. We will here be able to directly check several recent theoretical works on this rich subject.

Project coordination

Benjamin HUARD (Laboratoire Pierre Aigrain - CNRS - ENS Paris)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.


CNRS Laboratoire Pierre Aigrain - CNRS - ENS Paris

Help of the ANR 220,480 euros
Beginning and duration of the scientific project: August 2012 - 36 Months

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