Bosons outperform fermions: The thermodynamic advantage of symmetry

Myers, Nathan M.; Deffner, Sebastian

doi:10.1103/physreve.101.012110

Cited by 69 publications

(65 citation statements)

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“…Regarding the possibility to exploit permutation symmetry for quantum technological prospects, we could mention for example some recent proposals commenting on thermodynamic advantages of bosonic over fermionic symmetry [27], or the role of mixed symmetries in the quantum Gibbs paradox [28,29]. The role of mixed symmetry in quantum computation and information theory also deserves our attention and will be investigated in future work.…”

Section: Discussionmentioning

confidence: 99%

“…whereas the action of lowering operators S ij , i > j, is given by (26,27,30). From the definition (27) one can prove that…”

Section: U(l) Unirreps: Young Tableaux Gelfand Basis and Matrixmentioning

confidence: 99%

“…from the general expressions (23,26,27). With all this whole mathematical arsenal, we are now ready to tackle the analysis of the Hamiltonian (9) spectrum according to permutation symmetry, and the structure of the low-energy states inside each symmetry sector.…”

Section: U(l) Unirreps: Young Tableaux Gelfand Basis and Matrixmentioning

confidence: 99%

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Role of mixed permutation symmetry sectors in the thermodynamic limit of critical three-level Lipkin-Meshkov-Glick atom models

2021

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We introduce the notion of Mixed Symmetry Quantum Phase Transition (MSQPT) as singularities in the transformation of the lowest-energy state properties of a system of identical particles inside each permutation symmetry sector µ, when some Hamiltonian control parameters λ are varied. We use a three-level Lipkin-Meshkov-Glick (LMG) model, with U (3) dynamical symmetry, to exemplify our construction. After reviewing the construction of U (3) unirreps using Young tableaux and Gelfand basis, we firstly study the case of a finite number N of three-level atoms, showing that some precursors (fidelity-susceptibility, level population, etc.) of MSQPTs appear in all permutation symmetry sectors. Using coherent (quasi-classical) states of U (3) as variational states, we compute the lowest-energy density for each sector µ in the thermodynamic N → ∞ limit. Extending the control parameter space by µ, the phase diagram exhibits four distinct quantum phases in the λ-µ plane that coexist at a quadruple point. The ground state of the whole system belongs to the fully symmetric sector µ = 1 and shows a four-fold degeneracy, due to the spontaneous breakdown of the parity symmetry of the Hamiltonian. The restoration of this discrete symmetry leads to the formation of four-component Schrödinger cat states.

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Section: Discussionmentioning

confidence: 99%

“…whereas the action of lowering operators S ij , i > j, is given by (26,27,30). From the definition (27) one can prove that…”

Section: U(l) Unirreps: Young Tableaux Gelfand Basis and Matrixmentioning

confidence: 99%

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Role of mixed permutation symmetry sectors in the thermodynamic limit of critical three-level Lipkin-Meshkov-Glick atom models

2021

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“…Similarly, harmonic quantum Otto engines reach the Curzon-Ahlborn efficiency in the quasistatic limit [8,9]. More recently, it was demonstrated that the efficiency of endoreversible Otto engines at maximal power depends on the equation of state, i.e., the nature of the working medium [10][11][12][13][14] and the specific implementation of the power stroke [15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Endoreversible Otto Engines at Maximal Power

Smith

Pal

Deffner

2020

Journal of Non-Equilibrium Thermodynamics

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Despite its idealizations, thermodynamics has proven its power as a predictive theory for practical applications. In particular, the Curzon–Ahlborn efficiency provides a benchmark for any real engine operating at maximal power. Here we further develop the analysis of endoreversible Otto engines. For a generic class of working mediums, whose internal energy is proportional to some power of the temperature, we find that no engine can achieve the Carnot efficiency at finite power. However, we also find that for the specific example of photonic engines the efficiency at maximal power is higher than the Curzon–Ahlborn efficiency.

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“…In this cycle, the results of the efficiency depend on the nature of the working substance (through its energy spectrum) and the contributions of work and heat are separate in its stages, which facilitates theoretical modelling. These characteristics favor its extension to its quantum version, which has been studied extensively in recent years [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ].…”

Section: Introductionmentioning

confidence: 99%

Otto Engine: Classical and Quantum Approach

Peña

Negrete

Cortés

et al. 2020

Entropy

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In this paper, we analyze the total work extracted and the efficiency of the magnetic Otto cycle in its classic and quantum versions. As a general result, we found that the work and efficiency of the classical engine is always greater than or equal to its quantum counterpart, independent of the working substance. In the classical case, this is due to the fact that the working substance is always in thermodynamic equilibrium at each point of the cycle, maximizing the energy extracted in the adiabatic paths. We apply this analysis to the case of a two-level system, finding that the work and efficiency in both the Otto’s quantum and classical cycles are identical, regardless of the working substance, and we obtain similar results for a multilevel system where a linear relationship between the spectrum of energies of the working substance and the external magnetic field is fulfilled. Finally, we show an example of a three-level system in which we compare two zones in the entropy diagram as a function of temperature and magnetic field to find which is the most efficient region when performing a thermodynamic cycle. This work provides a practical way to look for temperature and magnetic field zones in the entropy diagram that can maximize the power extracted from an Otto magnetic engine.

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Bosons outperform fermions: The thermodynamic advantage of symmetry

Cited by 69 publications

References 100 publications

Role of mixed permutation symmetry sectors in the thermodynamic limit of critical three-level Lipkin-Meshkov-Glick atom models

Role of mixed permutation symmetry sectors in the thermodynamic limit of critical three-level Lipkin-Meshkov-Glick atom models

Endoreversible Otto Engines at Maximal Power

Otto Engine: Classical and Quantum Approach

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