A study published in Physical Review Letters (PRL) describes a “Gambling Carnot Engine” that scientists claim can achieve 100% efficiency while also enhancing power output.
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The scientists introduce a heat engine regulated by feedback that cleverly utilizes thermal fluctuations at the tiny level, creating innovative opportunities for energy collection in nano-sized devices.
The study, headed by Dr. Édgar Roldán of the Abdus Salam International Center for Theoretical Physics, questions two hundred years of thermodynamic theory by introducing a technique that aims to exceed what was previously seen as an unbreakable barrier in physics: the Carnot efficiency limit.
“I’ve always been intrigued by the inner workings of engines, ranging from those in cars to more advanced mechanisms, whether man-made like solar panels or natural like cells and living organisms,” Roldán said to the Muara Digital Team, discussing the inspiration behind his research.
Strategic gambling
Standard heat engines, such as the widely recognized Carnot engine, are limited by the maximum Carnot efficiency: η = 1 – (Tc/Th), where Tc and Thspecify the temperatures of the cold and hot heat sources, respectively.
This restriction, set by Sadi Carnot in 1824, has been viewed as definitive for two hundred years. Going beyond this threshold under classical thermodynamics would mean breaking the second law of thermodynamics.
The gambling Carnot engine (GCE) integrates a betting approach based on game theory and applied within the realm of thermodynamics. The system employs an external controller or “demon,” inspired by Maxwell’s famous hypothetical scenario, to carry out calculated actions based on defined standards.
The word ‘gambling’ was introduced in an earlier publication by some of us,Thermodynamics of gambling demons,’ published in PRL in 2021,” Roldán explained.
A comparison to gambling can be made, such as in blackjack, where players may choose to play a round or not based on the cards they hold, and also adhere to a particular rule.
The breakthrough focuses on the engine’s constant-temperature compression process.
At this stage, the particle would typically experience slow compression as the trap stiffness rises gradually, a process that demands significant energy input.
Nevertheless, the demon constantly tracks the particle’s location through rapid laser interferometry during this compression phase.
If the particle passes through the trap center (position x = 0) before a set time limit, the system instantly transitions to the final compressed state without any work being required.
The workings of minute-level efficiency
The engine functions by utilizing a colloidal particle—a tiny polystyrene sphere floating in water and held in place by concentrated laser beams. Unlike traditional engines that use pistons and cylinders, this system at the nanoscale modifies the particle’s confinement potential to create thermodynamic cycles.
“The concept of the GCE is to merge the primary method of energy extraction in a heat engine (transforming some heat from a hot reservoir into usable work, similar to a car’s engine) with that of an information-based machine (implementing feedback at particular times, akin to Maxwell’s demon),” Roldán explained.
The competitive edge arises from utilizing Brownian motion, which leads the particle to move erratically near the trap’s center.
The particle usually moves within a few hundred nanometers of its equilibrium point because of thermal energy caused by molecular collisions in the surrounding water.
The scientists found that this gambling approach results in a survival chance that decreases exponentially as the cycle time increases, indicating that efficiency improves with longer operational times. In the quasistatic limit, efficiency gets very close to 100%.
Revising effectiveness within inherent constraints
The assertion of exceeding Carnot efficiency requires a thorough understanding within the framework of thermodynamics. Roldán emphasizes that their definition aligns with traditional thermodynamics while uncovering fresh opportunities via information handling.
“We rely on the traditional concept of efficiency, meaning the ratio of the work obtained each cycle compared to the heat absorbed each cycle, with both values averaged across numerous machine operations,” he explained.
We demonstrate that this fraction can surpass the Carnot limit in the GCE, and can even attain a value of one, representing a 100% conversion of the heat input into extracted work.
The difference is related to factoring in the expense of information processing. Although the transformation from heat to mechanical energy can surpass traditional limits, the overall energy account—covering both information gathering and handling—adheres to basic thermodynamic rules when fully examined.
“If we consider the cost of erasing information regarding the particle’s position in each cycle when calculating efficiency, we arrive at a different definition of efficiency that adheres to the Carnot limit,” Roldán observed.
From concept to laboratory practicality
The scientists employed authentic parameters derived from a prior experimental investigation.
We are sure that our theoretical concept can be implemented in the laboratory rapidly,” Roldán said. “All our numerical results were obtained using practical experimental parameters that were taken from aprevious workof ours, which achieved the first ever Carnot machine using a polystyrene sphere held in optical tweezers.”
The primary experimental difficulties focus on fast position tracking and immediate feedback execution. The study shows that sampling rates exceeding 100 kilohertz are essential; when this level is not met, performance declines considerably because of detection lags that hinder the best timing for zero-cost interventions.
“Our concepts, along with comparable ones in the growing area of stochastic thermodynamics, have thus far served as proof of principle for what might guide the development of practical nanomachines that surpass traditional thermodynamic boundaries,” Roldán explained.
Created for you by our writerTejasri Gururaj,edited by Gaby Clark, and verified and examined byRobert Egan—this article is the outcome of dedicated human effort. We depend on readers like you to maintain independent science journalism. If this coverage is important to you, please consider adonation (especially monthly).
More information:Tarek Tohme et al., Gambling Carnot Engine,Physical Review Letters (2025). DOI: 10.1103/w8cx-xx1z
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