Energy quantization enhances the performance of single-atom heat machines

May 11, 2018 by Lisa Zyga, Phys.org feature
Illustration of a situation in which work cannot be extracted from a classical ideal gas, but can be extracted from a quantum one. Credit: Gelbwaser-Klimovsky et al. ©2018 American Physical Society

Physicists have demonstrated that energy quantization can improve the efficiency of a single-atom heat engine to exceed the performance of its classical counterpart. Energy quantization, in which the energy levels of a system occur only in discrete values, is a quintessential feature of quantum systems and differs from the continuous energy levels that occur in classical systems.

The physicists, David Gelbwaser-Klimovsky at Harvard University and coauthors, have published a paper on using energy quantization to improve the performance of heat machines in a recent issue of Physical Review Letters.

In their work, the researchers compared the performance of classical and quantum heat machines, which convert heat into work. In the classical version, a compressible working substance (usually a gas) is required for operation. When the working substance is heated, it expands and drives the engine's mechanical motion. In practice, it can be experimentally challenging to reach the large compression ratios needed for high performance. However, in the quantum version with quantized energy levels, the does not require a compressible working substance, but instead can function with incompressible working substances.

So overall, when considering energy quantization in a heat engine, the classical paradigms break down and large compression ratios are no longer needed to obtain highly efficient heat engines. As the scientists demonstrated, the appropriate manipulation of energy levels leads to higher efficiencies and opens the doors to realizing heat machines that are classically inconceivable.

The physicists also showed that, although quantization can improve heat engine efficiency, the efficiency is still subject to the Carnot limit—the fundamental limit on the efficiency of any . In addition, the performance improvement only occurs when the quantized are inhomogenously scaled, which is a regime that so far has received little attention. In the future, the researchers plan to further investigate this regime, as well as explore different kinds of working substances, such as those composed of interacting or indistinguishable particles.

Explore further: Miniaturised 'heat engines' could power nanoscale machines of the future

More information: David Gelbwaser-Klimovsky, Alexei Bylinskii, Dorian Gangloff, Rajibul Islam, Alán Aspuru-Guzik, and Vladan Vuletic. "Single-Atom Heat Machines Enabled by Energy Quantization." Physical Review Letters. DOI: 10.1103/PhysRevLett.120.170601

Also at arXiv:1705.11180 [quant-ph]

Related Stories

Physicists investigate fundamental limits of quantum engines

August 4, 2017

(Phys.org)—Quantum engines are known to operate differently than—and in some cases, outperform—their classical counterparts. However, previous research on the performance of quantum engines may be overestimating their ...

Nanoscale heat engine exceeds standard efficiency limit

January 27, 2014

(Phys.org) —In 2012, a team of physicists from Germany proposed a scheme for realizing a nanoscale heat engine composed of a single ion. Like a macroscale heat engine, the theoretical nanoscale version can convert heat ...

Thin film converts heat from electronics into energy

April 16, 2018

Nearly 70 percent of the energy produced in the United States each year is wasted as heat. Much of that heat is less than 100 degrees Celsius and emanates from things like computers, cars or large industrial processes. Engineers ...

What is quantum in quantum thermodynamics?

October 12, 2015

(Phys.org)—A lot of attention has been given to the differences between the quantum and classical worlds. For example, quantum entanglement, superposition, and teleportation are purely quantum phenomena with no classical ...

Recommended for you

Scientists design new material to harness power of light

December 17, 2018

Scientists have long known that synthetic materials—called metamaterials—can manipulate electromagnetic waves such as visible light to make them behave in ways that cannot be found in nature. That has led to breakthroughs ...

Pedestrians keep a 75 cm comfort zone to prevent collisions

December 17, 2018

Pedestrians are constantly avoiding collisions with oncoming people. Meters in advance they unconsciously change their walkway to pass each other. Physicists at Eindhoven University of Technology in collaboration with American ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

flueninsky
2.7 / 5 (7) May 12, 2018
Energy quantization
In the 60, and 70 there was talk of energy and friction coming in discrete packages of quanta then it all seemed to disappear, it's good to see its emergence.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.