Russian scientists have found a way to create a quantum device that violates the second law of thermodynamics and has an efficiency of virtually 100%, according to an article published in the journal Physics Review A.
“Any heat engine consists of a heater, which is, in fact, a source of energy, and a refrigerator, the task of which is to cool the working fluid of the engine. The refrigerator lowers the entropy of the motor and inevitably wastes some of the thermal energy from the heater. That is why the efficiency of a heat engine never reaches 100%,”explains Andrey Lebedev, an employee of the Technical University of Zurich and MIPT in Dolgoprudny.
One of the foundations of modern physics and cosmology is the concept of the so-called arrow of time - the postulate that time in our Universe moves exclusively in one direction, from the past to the future. In other words, we move through four-dimensional space in only one direction along the time axis, and it is impossible to "rewind" time back.
From the point of view of physics, this is manifested in the fact that over time, the disorder, chaos of the universe, a state that scientists call entropy, is steadily growing. For example, this process manifests itself in how the state of the energy of the Universe changes. The principle, which scientists often call "the second law of thermodynamics", is considered an unbreakable rule governing the life of the entire universe at all levels.
Gordey Lesovik and Andrey Lebedev. Photo: MIPT
A year ago, scientists from the Moscow Institute of Physics and Technology under the leadership of Gordey Lesovik from the Institute for Theoretical Physics of the Russian Academy of Sciences discovered that the second law of thermodynamics can be violated at the quantum level. This opened the way for the creation of a quantum analogue of the famous demon Maxwell - a hypothetical creature that sorts out fast and slow molecules.
This idea prompted scientists to think that such quantum "demons" can be used to create a machine whose efficiency will be 100%. For its development, scientists propose using two pairs of qubits - elementary computational modules and memory cells of quantum computers, interconnected at the quantum level.
The qubits in the engine of Lesovik and his colleagues perform two functions - they absorb heat and allow "teleporting" excess entropy outside the system, playing the role of Maxwell's demon. This allows the device to actually achieve a state equivalent to a perpetual motion machine of the second kind.
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In fact, of course, this device is not a perpetual motion machine - as Lesovik explains, for its operation it is necessary to constantly update the “demonic” qubits, which cleanse the system of entropy by cooling them in a special way. On the other hand, this is done outside the device itself, which allows us to say that formally the second law of thermodynamics is nevertheless violated inside it.
Now Lesovik and his colleagues are implementing this idea in practice, creating a similar perpetual motion machine based on superconducting qubits - transmons.
