Pith. sign in

REVIEW 3 major objections 4 minor 30 references

Thermodynamics in a split Hilbert space: Quantum impurity at the edge of a one-dimensional superconductor

T0 review · 3 major / 4 minor · reviewed 2026-08-05 · deepseek-v4-flash

Pith's one-line read A magnetic impurity at the edge of a one-dimensional superconductor can carry an entropy that overshoots the free-spin value ln 2 at intermediate temperatures.

desk verdict New TBA derivation yielding a measurable entropy overshoot, but the main text has a sign error and the tower-counting fractions are asserted, so the central quantitative claim isn't yet established. read the letter →

arxiv 2508.19330 v1 pith:WWUXS7T5 submitted 2025-08-26 cond-mat.str-el cond-mat.supr-conhep-thmath-phmath.MPquant-ph

classification cond-mat.str-elcond-mat.supr-conhep-thmath-phmath.MPquant-ph MSC 82B2382D55
keywords Yu–Shiba–RusinovboundstatesimpurityentropyovershootthermodynamicBetheansatzHilbertspacefragmentationintotowersKondoinasuperconductorboundaryquantumphasetransitionmidgapexactlysolvablemodel
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

The paper studies a single spin-1/2 impurity at the open edge of a one-dimensional superconducting wire, a model that is exactly solvable by Bethe ansatz. It claims that the finite-temperature impurity entropy is organized by a splitting of the Hilbert space into distinct towers of excitations whose relative sizes are phase-dependent. In the Kondo phase the entropy flows monotonically from ln 2 at high temperature to 0 at low temperature, with the same critical exponents as the conventional Kondo model. In the Yu-Shiba-Rusinov (YSR) phases the entropy is non-monotonic and can overshoot ln 2, because thermal activation of a midgap bound state temporarily adds entropy; in the local-moment phase it stays near ln 2 with only small bumps that fade as δ grows. If correct, the paper provides closed-form analytic expressions for the impurity free energy and entropy across all four phases, including thermodynamic signatures that do not exist in a gapless host.

What carries the argument

Excitation towers: distinguished families of Bethe-ansatz eigenstates built on a small set of base states—|K⟩, |U⟩, |B⟩, and |̃U⟩—that differ by purely imaginary boundary string solutions of the Bethe equations. The impurity partition function is the sum over towers of e^{−β F_imp^{(Ti)}}, and each tower free energy is a convolution of ln(1 + η_n) with 1/cosh kernels, where η_n solve the thermodynamic Bethe ansatz equations. The entropy decomposes into a weighted ensemble average over towers (the mixing term) plus an activation term peaked when the temperature matches the midgap bound-state energy Eδ.

What would settle it

Compute the tower weights by exact diagonalization of the attractive Hubbard chain with an edge impurity used in the supplement, counting eigenstates in each boundary-root sector: if the numbers do not match the 3:1 ratio in YSR I and the 8:3:1 ratio in YSR II, the decomposition fails. Alternatively, measure impurity entropy of a quantum dot at the end of a superconducting nanowire via charge sensing: the central claim predicts a bump above ln 2 near T ≈ |Eδ| that should move and disappear as the gate-tuned phase boundary δ = 1 is crossed.

Watch

Extended reading notes

Core claim

The central claim is that the spectrum of this boundary impurity problem organizes into excitation towers that change with the RG-invariant parameter δ, and that each tower carries its own free energy. In the Kondo regime all states form one tower built on the fully screened singlet |K⟩. For 1/2 < δ < 1 (YSR I) there are two towers built on the unscreened |U⟩ and screened |B⟩ states, with relative weights 3/4 and 1/4; for 1 < δ < 3/2 (YSR II) and δ > 3/2 (local moment) there are three towers, with weights (4/6, 1/4, 1/12) in YSR II and floor-function expressions in the local-moment regime. Summing tower Boltzmann weights gives the impurity free energy F_imp(T); differentiating gives the entr

Load-bearing premise

The counting that each phase's Hilbert space is fully exhausted by the proposed towers (3/4 and 1/4 in YSR I; 4/6, 1/4, 1/12 in YSR II) and the analyticity of the contour shifts used to evaluate the tower free energies are the load-bearing premises; if either fails, the closed-form free energy and the entropy overshoot are not established.

Editorial extensions

If this is right

  • The predicted entropy overshoot above ln 2 gives a measurable thermodynamic fingerprint of YSR midgap states, distinguishing them from the monotonic Kondo flow.
  • The Kondo phase retains the conventional critical exponents despite the gapped host, so the universal screening behavior is unchanged there.
  • The fixed-particle-number treatment in the supplement shifts tower energies by the hole mass m and can produce negative entropy dips near δ ≈ 0.5, making the grand-canonical and fixed-N predictions experimentally distinguishable.
  • The tower decomposition generalizes the TBA approach to any integrable impurity or defect that generates boundary bound states, not only YSR superconductors.
  • In the local-moment phase the impurity is only asymptotically decoupled: S_imp approaches ln 2 in both limits, but small intermediate-temperature bumps persist and vanish as δ → ∞.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • I would expect the same entropy-overshoot mechanism to appear in other integrable boundary problems with boundary strings, such as an impurity at the edge of a gapped spin chain, where the floor-function tower weights could be checked by exact diagonalization of short chains.
  • A direct experimental test could use charge-sensing entropy measurements on a quantum dot attached to a superconductor-semiconductor nanowire: the bump should appear near T ≈ |Eδ| and move or disappear as the gate-tuned phase boundary δ = 1 is crossed.
  • The paper leaves open whether the tower structure survives away from integrability; if it does, the overshoot should be robust to weak non-integrable perturbations, which could be tested with tensor-network simulations of the lattice model.
  • The fixed-N variant's predicted negative entropy dips are a sharp falsifiable signature: a measurement protocol that fixes particle number should see a dip, while a grand-canonical setup should see only the overshoot.
Share X Bluesky LinkedIn Reddit HN

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

3 major / 4 minor

Summary. This Letter studies the finite-temperature impurity thermodynamics of an integrable one-dimensional superconductor with a boundary magnetic impurity. Using the Bethe-ansatz solution of Refs. [4,5], the authors propose that the Hilbert space in each phase decomposes into distinct 'excitation towers' whose number changes across the four phases (Kondo, YSR I, YSR II, local moment). They derive TBA-based expressions for the impurity free energy and entropy in each phase, and report a monotonic Kondo entropy flow, non-monotonic YSR/local-moment entropies with an overshoot above ln 2, and closed-form saturation values. Numerical TBA solutions and exact diagonalization of a small related lattice model are presented in the supplementary material to support the qualitative entropy curves.

Significance. If the central derivation is correct, this is a substantial contribution to integrable impurity thermodynamics: it extends beyond conventional TBA to a gapped superconductor with boundary-bound modes, gives explicit tower-resolved free energies, and makes concrete, falsifiable predictions for impurity entropy overshoots and saturation values. The work is parameter-free, builds on previously solved Bethe-ansatz equations rather than fitting, and includes both numerical TBA and exact-diagonalization checks. These are real strengths. However, the manuscript currently contains a sign inconsistency in a central equation, an unproven tower-counting step on which the decomposition rests, and a contour-shift step in the supplementary that is not justified. These issues must be resolved before the central claims can be accepted.

major comments (3)
  1. [Main text, Eq. (10); Supplementary Eq. (S.69)] The printed sign in Eq. (10) contradicts the text and the supplementary derivation. As written, F(T2)_imp = -T/4 ∫ Σ ln(1+η1)/cosh(π(λ+iυδ)); with η1(T→∞)→3 this gives S(T2)(∞)=+ln2, whereas the text and Fig. 1 require S(T2)(∞)=-ln2. The supplementary derivation in Eq. (S.69) has the opposite overall sign. Since the entropy overshoot decomposition and the values S(T2)(∞)=-ln2, S(T1)(∞)=ln(3/2) follow directly from these formulas, Eq. (10) must be corrected and the two equations reconciled.
  2. [Main text after Fig. 2; Supplementary Sec. S.1C] The tower-counting fractions are asserted without proof. The main text states that in YSR-I the towers contain 3/4 and 1/4 of the states, and in YSR-II the fractions are 4/6, 1/4, and 1/12 (with analogous δ>3/2 formulas), but no counting calculation is shown. The supplement merely says that 'counting the states ... shows' that two towers do not exhaust the Hilbert space, and then asserts a third tower. The partition-function decomposition Z=Σ_i e^{-βF_Ti}, the saturation entropies, and the entropy overshoot all depend on these towers and their relative weights. The ED in Sec. S.5 tests a related lattice model and does not verify the tower weights or the closed-form free-energy expressions. A derivation or an explicit state-count in the supplement is needed.
  3. [Supplementary Eq. (S.65) and Eq. (S.69)] The analytic continuation/contour-shift step is not justified. Eq. (S.65) is stated to be valid only for |ζ|<1/2, but the passage from the first to the second expression in Eq. (S.69) replaces a shift δ-1 (which lies inside the strip for δ∈(1/2,1)) by δ (which lies outside the strip). The contour shift can pick up pole contributions from the 1/cosh kernel. The authors should either show these residues vanish, or identify them explicitly and show that they are already accounted for by the |Eδ| term in Eq. (10). As written, the derivation of the central YSR-I free energy is incomplete.
minor comments (4)
  1. [Abstract] The abstract claims 'closed-form analytic expressions across the entire phase diagram.' At finite temperature, η_n(λ) are obtained by numerically solving the infinite TBA hierarchy (Supplementary Sec. S.3); only the asymptotics are literally closed form. Please qualify the wording, e.g., 'exact integral representations in terms of the TBA functions.'
  2. [Main text after Eq. (10)] The phrase '∀d ∪ δ ∈ (0,1)' is imprecise; d is real or imaginary and δ is defined for d=iδ. Please restate the parameter ranges explicitly.
  3. [Supplementary Sec. S.2B] F(T2)_0 is introduced and then set to zero later; the reader should be told at the point of introduction that this is a constant ground-state energy and will be absorbed.
  4. [Supplementary Sec. S.3] The numerical TBA solution is validated only by empirical convergence checks. The authors state no formal error bounds; this is acceptable for a numerical study, but it should be labeled as numerical evidence rather than part of the exact analytic derivation.

Circularity Check

0 steps flagged · score 2.0 of 10

No significant circularity: the finite-T impurity thermodynamics is a new derivation from the previously solved Bethe-ansatz spectrum; the asserted tower-counting weights are an unproven supporting assumption, not a circular input.

full rationale

The central derivation takes the Bethe-ansatz equations (2)-(3) from the authors' earlier solution [4,5], derives the TBA hierarchy (5)-(6), and evaluates the impurity free energy via the tower-decomposed expressions (9)-(10) and their YSR-II/local-moment analogues. No parameter is fitted to the target entropy curves; Simp(T) is obtained by differentiating the resulting Fimp(T). The entropy overshoot follows from the mixing/activation decomposition (Eq. 11) after inserting the asymptotic eta_n limits (Eqs. 7-8), so it is a consequence of the formalism, not an input. The self-citations to [4,5] supply the integrable spectrum and phase classification, but they are parameter-free results that do not already contain the predicted finite-T entropy curves; the present calculation of the partition-function towers and free energies is new, so the self-citation is not load-bearing in a circular sense. The main genuine weaknesses are gaps in support, not circularity. The Hilbert-space counting fractions after Fig. 2 and in Supp. S.1C are asserted: Supp. S.1C says 'counting the states generated by these two towers shows that their total dimension does not sum to the full Hilbert space dimension 2 x 2^N' without exhibiting the count, and the fractions 3/4, 1/4; 4/6, 1/4, 1/12; etc. are stated without derivation. In addition, the contour-shift step in Supp. S.2B uses the analytic continuation (S.65) whose stated strip is |zeta| < 1/2, while some shifted arguments approach delta in (1/2,1), leaving the shift outside the stated domain. These are unproven or delicate steps that could alter the tower weights and hence the entropy profile, but they are independent inputs, not restatements of the claimed entropy result. Thus there is no exhibited reduction of the prediction to a fit or to a self-citation chain; the paper is self-contained in its thermodynamic derivation aside from the unsupported counting assertion.

Assumptions & free parameters 0 free parameters · 5 assumptions · 0 invented entities

The central calculation assumes the Bethe-ansatz spectrum from prior work (same group) and the standard TBA framework; no free parameters are fitted. The main additional input is the string hypothesis and the unproven tower counting, plus analytic continuation of TBA identities beyond the stated strip.

assumptions (5)
  • domain assumption String hypothesis: all solutions of the BAE have the form of strings (S.4) plus the boundary strings (S.5).
    Used to derive the TBA equations and the tower structure; unproven in this paper, standard but not rigorous for all states.
  • domain assumption Phase classification and the RG-invariant parameter d/delta are taken from prior work (Refs [5]).
    The paper relies on the earlier ground-state analysis to define the four phases and the tower base states.
  • domain assumption The free energy separates as F = F_bulk + F_edge + F_imp, with the impurity part obtained from the ratio Z/Z0.
    Standard in boundary impurity problems; the edge contribution g(T) is not computed.
  • ad hoc to paper Analytic continuation identity Eq. (S.65) is valid and can be applied with shifts up to |zeta| < 1/2; the subsequent contour shifts used to obtain Eq. (10) neglect pole contributions for delta > 1/2.
    The derivation of the YSR-I free-energy formulas involves shifting integration contours outside the stated strip, which may change the result by residue contributions.
  • ad hoc to paper The excitation towers T1, T2 (and T3) exhaust the Hilbert space with the stated fractions (3/4:1/4 in YSR-I; 4/6:1/4:1/12 in YSR-II).
    The counting fractions are stated without derivation; they underpin the partition-function sum.

how reviews work

0 comments
Cite this review

Pith. "Pith review of Thermodynamics in a split Hilbert space: Quantum impurity at the edge of a one-dimensional superconductor." pith.science (2026). https://pith.science/paper/WWUXS7T5

@misc{pith2026250819330,
  author       = {Pith},
  title        = {Pith review of: Thermodynamics in a split Hilbert space: Quantum impurity at the edge of a one-dimensional superconductor},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/WWUXS7T5}},
  note         = {Machine review of arXiv:2508.19330}
}
abstract

We present a thermodynamic description of a single magnetic impurity at the edge of a superconducting wire. The impurity exhibits four phases $\unicode{x2014}$ Kondo, Yu-Shiba-Rusinov (YSR) I and II, and local moment $\unicode{x2014}$ a phase diagram richer than in the gapless case, contrary to the expectation that the effects of impurities in gapped hosts are less consequential. We derive the impurity contribution to free energy $F_{\rm imp}(T)$ and entropy in each phase: in Kondo phase, the entropy flows monotonically from $\ln 2$ (UV) to 0 (IR) with critical exponents same as that of the conventional Kondo model; in YSR phases, thermal activation of a midgap bound state produces entropy overshoots above $\ln 2$, saturating to $\ln 2$ at high $T$ and approaching either 0 or $\ln 2$ at low $T$ depending on whether impurity is screened or not; in the local-moment phase the impurity remains effectively decoupled, with entropy near $\ln 2$, with some intermediate-temperature features that progressively fade as $\delta \to 0$. These behaviors, including the entropy overshoots in the YSR and local-moment phases, stem from a splitting of the Hilbert space into distinct excitation towers: one in the Kondo phase, two in YSR~I, and three in YSR~II and the local-moment phase. Resolving these tower structures and thereby going beyond conventional TBA yields closed-form analytic expressions for the impurity contribution to the free energy and entropy across the entire phase diagram.

Figures

Figures reproduced from arXiv: 2508.19330 by the authors.

Figure 1
Figure 1. FIG. 1 [PITH_FULL_IMAGE:figures/full_fig_p001_1.png] view at source ↗
Figure 2
Figure 2. FIG. 2: The Hilbert space fragments into different [PITH_FULL_IMAGE:figures/full_fig_p002_2.png] view at source ↗
Figure 3
Figure 3. FIG. 3: Numerical solutions of the TBA for [PITH_FULL_IMAGE:figures/full_fig_p003_3.png] view at source ↗
Figures from the paper (9 more)
Figure 4
Figure 4. Figure 4: FIG. 4: The impurity entropy contribution for [PITH_FULL_IMAGE:figures/full_fig_p016_4.png]
Figure 5
Figure 5. Figure 5: FIG. 5: Representative impurity entropy [PITH_FULL_IMAGE:figures/full_fig_p017_5.png]
Figure 6
Figure 6. Figure 6: FIG. 6: Impurity entropy [PITH_FULL_IMAGE:figures/full_fig_p019_6.png]
Figure 7
Figure 7. Figure 7: FIG. 7: Temperature dependence of the impurity entropy [PITH_FULL_IMAGE:figures/full_fig_p021_7.png]
Figure 8
Figure 8. Figure 8: FIG. 8: Impurity entropy for representative value of [PITH_FULL_IMAGE:figures/full_fig_p023_8.png]
Figure 9
Figure 9. Figure 9: FIG. 9: YSR bound state energies [PITH_FULL_IMAGE:figures/full_fig_p025_9.png]
Figure 10
Figure 10. Figure 10: FIG. 10: The entire spectrum of the Hamiltonian Eq. ( [PITH_FULL_IMAGE:figures/full_fig_p026_10.png]
Figure 11
Figure 11. Figure 11: FIG. 11: Low-lying energy spectrum of the finite-size lattice Hamiltonian Eq.( [PITH_FULL_IMAGE:figures/full_fig_p026_11.png]
Figure 12
Figure 12. Figure 12: FIG. 12 [PITH_FULL_IMAGE:figures/full_fig_p027_12.png]

Discussion (0). Continue with ORCID to comment.

Reference graph

Works this paper leans on

30 extracted references · 18 canonical work pages

  1. [1]

    LUH, Bound state in superconductors with paramag- netic impurities, Acta Physica Sinica 21, 75 (1965)

    Y. LUH, Bound state in superconductors with paramag- netic impurities, Acta Physica Sinica 21, 75 (1965)

  2. [2]

    Shiba, Classical Spins in Superconductors, Progress of Theoretical Physics 40, 435 (1968)

    H. Shiba, Classical Spins in Superconductors, Progress of Theoretical Physics 40, 435 (1968)

  3. [3]

    A. I. Rusinov, Superconductivity near a Paramagnetic Impurity, Soviet Journal of Experimental and Theoreti- cal Physics Letters 9, 85 (1969)

  4. [4]

    P. R. Pasnoori, C. Rylands, and N. Andrei, Kondo im- purity at the edge of a superconducting wire, Phys. Rev. Res. 2, 013006 (2020)

  5. [5]

    P. R. Pasnoori, N. Andrei, C. Rylands, and P. Azaria, Rise and fall of yu-shiba-rusinov bound states in charge-conserving s-wave one-dimensional superconduc- tors, Physical Review B 105, 174517 (2022)

  6. [6]

    C. P. Moca, C. Hajd´ u, B. D´ ora, and G. Zar´ and, Spectral properties of fractionalized shiba states, arXiv preprint arXiv:2412.14627 (2024)

  7. [7]

    C. P. Moca, I. Weymann, M. A. Werner, and G. Zar´ and, Kondo cloud in a superconductor, Physical Review Let- ters 127, 186804 (2021)

  8. [8]

    Z.-Y. Wei, T. Shi, J. I. Cirac, and E. A. Demler, Kondo impurity in an attractive fermi-hubbard bath: Equi- librium and dynamics, arXiv preprint arXiv:2501.05562 (2025)

Show all 30 references
  1. [9]

    Kattel, A

    P. Kattel, A. Zhakenov, and N. Andrei, Kondo over- screening in the presence of superconductivity, arXiv preprint arXiv:2412.01924 (2024)

  2. [10]

    Kattel, A

    P. Kattel, A. Zhakenov, and N. Andrei, Competing color superconductivity and color kondo effect in quark matter, arXiv preprint arXiv:2507.11617 (2025)

  3. [11]

    Hartman, C

    N. Hartman, C. Olsen, S. L¨ uscher, M. Samani, S. Fallahi, G. C. Gardner, M. Manfra, and J. Folk, Direct entropy measurement in a mesoscopic quantum system, Nature Physics 14, 1083 (2018)

  4. [12]

    Child, O

    T. Child, O. Sheekey, S. L¨ uscher, S. Fallahi, G. C. Gardner, M. Manfra, A. Mitchell, E. Sela, Y. Kleeorin, Y. Meir, et al., Entropy measurement of a strongly cou- pled quantum dot, Physical Review Letters 129, 227702 (2022)

  5. [13]

    Kealhofer, C

    D. Kealhofer, C. Adam, M. J. Ruckriegel, P. Tomi´ c, B. Kratochwil, C. Reichl, Y. Meir, W. Wegscheider, T. Ihn, and K. Ensslin, Entropy of a double quantum dot, arXiv preprint arXiv:2508.09481 (2025)

  6. [14]

    P. R. Pasnoori, P. Azaria, C. Rylands, and N. An- drei, Emergent boundary supersymmetry in a one dimen- sional superconductor, arXiv preprint arXiv:2505.24777 (2025)

  7. [15]

    Supplemental material [link to be inserted by publisher] (2025), for detailed discussion of towers of eigenstates, eigenstate phase transition, and its signature in the im- purity free energy, and also exact diagonalization solution of a related lattice model

  8. [16]

    C.-N. Yang, C. P. Yang, et al., Thermodynamics of a one-dimensional system of bosons with repulsive delta- function interaction, Journal of Mathematical Physics 10, 1115 (1969)

  9. [17]

    Takahashi et al., Thermodynamics of one-dimensional solvable models (Cambridge university press Cambridge, 1999)

    M. Takahashi et al., Thermodynamics of one-dimensional solvable models (Cambridge university press Cambridge, 1999)

  10. [18]

    Andrei, K

    N. Andrei, K. Furuya, and J. Lowenstein, Solution of the kondo problem, Reviews of modern physics 55, 331 (1983)

  11. [19]

    Tsvelick and P

    A. Tsvelick and P. Wiegmann, Exact results in the theory of magnetic alloys, Advances in Physics 32, 453 (1983)

  12. [20]

    V. T. Rajan, J. H. Lowenstein, and N. Andrei, Thermo- dynamics of the kondo model, Phys. Rev. Lett. 49, 497 (1982)

  13. [21]

    Zar´ and, T

    G. Zar´ and, T. Costi, A. Jerez, and N. Andrei, Thermo- dynamics of the anisotropic two-channel kondo problem, Physical Review B 65, 134416 (2002)

  14. [22]

    Pozsgay, On o(1) contributions to the free energy in bethe ansatz systems: the exact g-function, Journal of High Energy Physics 2010, 1 (2010)

    B. Pozsgay, On o(1) contributions to the free energy in bethe ansatz systems: the exact g-function, Journal of High Energy Physics 2010, 1 (2010)

  15. [23]

    He and Y

    Y.-J. He and Y. Jiang, Exact g-function without strings, 6 arXiv preprint arXiv:2412.12869 (2024)

  16. [24]

    ground-state degeneracy

    I. Affleck and A. W. W. Ludwig, Universal noninteger “ground-state degeneracy” in critical quantum systems, Phys. Rev. Lett. 67, 161 (1991)

  17. [25]

    Friedan and A

    D. Friedan and A. Konechny, Boundary entropy of one- dimensional quantum systems at low temperature, Phys. Rev. Lett. 93, 030402 (2004)

  18. [26]

    Zhakenov, P

    A. Zhakenov, P. Kattel, and N. Andrei, Thermodynamics in a split hilbert space: Quantum impurity at the edge of the heisenberg chain, TBA (2025), to be published

  19. [27]

    Kattel, P

    P. Kattel, P. R. Pasnoori, J. Pixley, P. Azaria, and N. An- drei, Kondo effect in the isotropic heisenberg spin chain, Physical Review B 109, 174416 (2024)

  20. [28]

    Kattel, P

    P. Kattel, P. R. Pasnoori, J. H. Pixley, and N. Andrei, Edge modes and boundary impurities in the anisotropic heisenberg spin chain, Phys. Rev. B 111, 174430 (2025)

  21. [29]

    Y. Tang, P. Kattel, J. H. Pixley, and N. Andrei, Quan- tum zeno effect in noisy integrable quantum circuits for impurity models, Phys. Rev. B 111, 054313 (2025)

  22. [30]

    ln 1 + η⌈2δ⌉(λ) cosh π λ + iυ 2 (2δ − ⌊2δ⌋) − ln 1 + η⌊2δ⌋(λ) cosh π λ + iυ 2 (⌈2δ⌉ −2δ) # , F (T2) imp = T 4 X υ=± Z dλ

    E. H. Lieb and F.-Y. Wu, Absence of mott transition in an exact solution of the short-range, one-band model in one dimension, Physical Review Letters 20, 1445 (1968). 1 Supplementary Materials for ‘Thermodynamics in a split Hilbert space: Quantum impurity at the edge of a one-...

Pith tools

Reviewed August 5, 2026 · model on record in the stance chip above.