[Paper Review] Quantum limits to the second law and breach of symmetry

А. В. Никулов|arXiv (Cornell University)|May 20, 2005

Quantum and electron transport phenomena3 citations

TL;DR

This paper argues that quantum systems can violate the second law of thermodynamics through intrinsic symmetry breaking, particularly via persistent currents in mesoscopic loops that break time-reversal and spatial symmetries. It demonstrates that quantum coherent states in superconducting loops generate non-zero dc voltages under asymmetric conditions, enabling cumulative power output that exceeds thermal noise, thus challenging the classical view of entropy increase under equilibrium conditions.

ABSTRACT

Connection between an intrinsic breach of symmetry of equilibrium motion and violation of the second law is accentuated. An intrinsic breach only of clockwise - counter-clockwise symmetry of a circular equilibrium motion can be logical under equilibrium conditions, whereas a breach of right-left symmetry should be always an actual violation of the second law. The reader's attention is drawn to experimental evidence of an intrinsic breach of the clockwise - counter-clockwise symmetry of a circular equilibrium motion, well known as the persistent current. The persistent current is observed in mesoscopic normal metal, semiconductor and superconductor loops and the clockwise - counter-clockwise symmetry is broken because of the discrete spectrum of the permitted states of quantum charged particles in a closed loop. The quantum oscillations of the dc voltage observed on a segment of an asymmetric superconducting loop is experimental evidence of the intrinsic breach of the right-left symmetry and an actual violation of the second law.

Motivation & Objective

• To challenge the classical assumption that the second law of thermodynamics is universally inviolable under equilibrium conditions.
• To investigate how intrinsic symmetry breaking in quantum systems—particularly in mesoscopic loops—may lead to violations of the second law.
• To examine experimental evidence such as persistent currents and quantum oscillations in asymmetric superconducting loops as indicators of actual entropy reduction.
• To explore the implications of these findings for the fundamental status of the second law and its applicability at the quantum scale.

Proposed method

• Analyzes the symmetry properties of equilibrium motion, distinguishing between clockwise-counter-clockwise and right-left symmetry breaking.
• Applies quantum mechanics to closed loops, showing that discrete energy levels lead to persistent currents that break time-reversal and rotational symmetry.
• Examines the quantum oscillations of dc voltage in asymmetric superconducting loops as evidence of right-left symmetry breaking and non-equilibrium behavior.
• Compares Nyquist thermal noise (chaotic, incoherent) with coherent persistent current power (ordered, cumulative), highlighting the potential for net energy gain.
• Uses theoretical models of quantum superposition in superconducting loops to explain non-zero persistent currents even at flux quanta where classical expectations predict zero.
• Proposes that cumulative dc power from multiple asymmetric loops can exceed single-loop output, suggesting a mechanism for sustained energy extraction from equilibrium.

Experimental results

Research questions

• RQ1 Can intrinsic symmetry breaking in quantum systems lead to a violation of the second law of thermodynamics?
• RQ2 What is the role of persistent currents in mesoscopic loops in breaking time-reversal and spatial symmetries under equilibrium conditions?
• RQ3 How do quantum oscillations of dc voltage in asymmetric superconducting loops provide evidence of actual entropy reduction?
• RQ4 Why is right-left symmetry breaking incompatible with equilibrium, while clockwise-counter-clockwise symmetry breaking is not?
• RQ5 Can coherent quantum effects in macroscopic systems generate usable power without external energy input, challenging the Carnot principle?

Key findings

• Persistent currents in mesoscopic loops break clockwise-counter-clockwise symmetry due to discrete quantum states, providing a mechanism for non-zero motion under equilibrium conditions.
• Quantum oscillations of dc voltage in asymmetric superconducting loops demonstrate a breach of right-left symmetry and indicate an actual violation of the second law.
• The coherent, cumulative nature of persistent current power allows for output that exceeds thermal noise (Nyquist power), with experimental results showing a 20-fold increase in voltage amplitude across 20 loops.
• Theoretical analysis shows that quantum superposition in loops at half-flux quanta can sustain non-zero persistent currents, contradicting classical expectations of zero current at Φ = (n+0.5)Φ₀.
• The maximum persistent power is limited to ~10⁻¹² W at 1 K and ~10⁻⁸ W at 100 K, but cumulative effects in series configurations can significantly amplify usable output.
• The paper concludes that such quantum effects provide a plausible mechanism for apparent violation of the second law, challenging the classical belief in universal irreversibility and entropy increase.