REVIEW
Fermi surfaces and gauge-gravity duality
High Energy Physics - Theory · Submitted 26 Apr 2011 · 81 references
Pith's verdict: A useful survey of compressible quantum matter with two new mean-field toy models; the bridge to full ABJM and N=4 SYM is explicitly a conjecture, not a derivation, and the paper mostly says so.
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Referee report
The paper
The paper claims
The compressible phases of condensed matter — Fermi liquid, non-Fermi liquid, and fractionalized Fermi liquid — should also appear in the ABJM and $N=4$ super Yang-Mills theories once a chemical potential is turned on.
The reading
What carries the argument
The load-bearing tool is the generalized Luttinger theorem of Eq. (1.4), $langle Qrangle = sum_{ell,in,mathrm{fermions}} q_ell V_ell$, which ties the conserved charge density to the momentum-space volumes enclosed by every fermionic Fermi surface, including composite or fractionalized fermions introduced through a Hubbard-Stratonovich decoupling. A Fermi surface is defined precisely as the locus where the inverse Green's function vanishes at zero frequency, $G_ell^{-1}(k=k_F,omega=0)=0$, together with the mild condition that the imaginary part of the inverse Green's function vanish away from that locus as $omega to 0$. This definition is what lets the theorem apply beyond Landau Fermi liquid theory, to surfaces with non-Fermi liquid singularities of the form $G^{-1}(k,omega)=q^{1-eta}Phi(omega/q^{z/2})$. The theorem does the bookkeeping work of the whole paper: it converts a single number, the charge density, into a constraint on how many Fermi surfaces can exist and how large they are, and it is what makes the FL* phase distinctive, because there the Fermi volume seen by gauge-invariant probes is smaller than the total density, with the deficit carried by hidden gauge-charged surfaces.
Extended reading notes
Core claim
The paper's central claim is that the compressible phases already catalogued in condensed matter — Fermi liquid (FL), non-Fermi liquid (NFL) with Fermi surfaces blurred by gapless gauge fluctuations, and fractionalized Fermi liquid (FL*) with coexisting gauge-charged and gauge-neutral Fermi surfaces — are also present in models built from the symmetries and particle content of the ABJM theory in $d=2$ and $N=4$ super Yang-Mills in $d=3$ after a chemical potential is applied. The argument runs through two toy Lagrangians, $L_1$ in Eq. (5.2) and $L_3$ in Eq. (6.2), in which the gauge group is reduced to $U(1)$ or $SU(2)$, flavor indices are dropped, and the particles are treated non-relativistically. Minimizing the mean-field free energy subject to gauge-charge neutrality yields the phase diagrams of Figs. 4 through 12, and those diagrams contain FL, NFL, and FL* phases in the ABJM-inspired case, and FL plus superfluid phases in the SYM-inspired case. A sharp structural result separates the two: in $L_1$ the fermion pairing term couples to a boson pair $b_+b_-$, so the energy correction behaves as $g_1^2|b_+|^2|b_-|^2$ times a logarithm and can have a stable minimum at $b_+=b_-=0$, which is what permits NFL and FL* phases to survive; in $L_3$ the pairing couples to a single boson $g_1^2|Phi^a|^2$, giving the standard BCS logarithm that makes any phase with $lambda^a$ Fermi surfaces unstable to superfluidity, so no NFL or FL* appears there.
Load-bearing premise
The bridge from condensed matter to the supersymmetric theories runs entirely through simplified toy Lagrangians that reduce the gauge group to $U(1)$ or $SU(2)$, drop flavor indices, make the particles non-relativistic, and are analyzed at mean-field level with gauge fluctuations omitted; the paper assumes, without deriving it, that this reduction preserves the qualitative phase structure of the full theories.
Editorial extensions
If this is right
- If the toy models are faithful, the zero-temperature phase diagrams of the ABJM theory in $d=2$ and $N=4$ SYM in $d=3$ at nonzero chemical potential contain NFL and FL* phases, not merely the superconducting or superfluid phases that holographic studies had already found.
- The FL* phase offers a concrete target for gravity duals: gauge-neutral fermions scatter strongly off a gauge-charged sector, so a small Fermi volume seen by charge-carrying probes becomes a prediction to look for in a classical gravity solution.
- The Luttinger count gives an experimentally checkable bookkeeping rule for any compressible state whose global charge symmetry is unbroken, even when the quasiparticles near the Fermi surface are not Fermi liquid-like.
- Which chemical potential is turned on matters qualitatively: with $mu_1neq 0$ the scalar is doubly charged and cannot mix with fermion pairs, so no deconfined NFL or FL* phases appear, whereas with $mu_1=mu_2neq 0$ the scalar carries unit charge, the pairing term $g_1$ is forbidden, and deconfined FL* and NFL phases reappear in Figs. 11 and 12.
Reading between the lines
- The pairing instability the paper flags as an affliction of every NFL and FL* phase — gauge-boson exchange driving Cooper pairing that gaps the Fermi surfaces — is the natural first thing a dual gravity computation should be checked against, since a classical bulk solution with a charged scalar condensate would be the gravity-side image of that instability.
- Because the Luttinger constraint is stated for any unbroken global $U(1)$, it supplies a consistency check on holographic models independent of their details: any proposed gravity dual of a compressible state that reports a charge density inconsistent with its fermionic Fermi volumes is either not in the phase it claims or has broken the symmetry.
- The paper's reduction to non-relativistic toy Lagrangians is a controlled-looking but undemonstrated step; a natural follow-up is to ask whether the same phase diagrams survive keeping the full $U(N)times U(N)$ or $SU(N)$ gauge group and relativistic dispersion at leading order in large $N$.
- The distinction between the two models turns on whether the pairing term couples to one boson or a boson pair, which suggests a general selection rule: whether a holographic theory at finite density admits deconfined NFL phases depends on the charge assignment of its scalar sector under the residual symmetry, a criterion that could be applied to other supergravity truncations.
Original abstract
We give a unified overview of the zero temperature phases of compressible quantum matter: i.e. phases in which the expectation value of a globally conserved U(1) density, Q, varies smoothly as a function of parameters. Provided the global U(1) and translational symmetries are unbroken, such phases are expected to have Fermi surfaces, and the Luttinger theorem relates the volumes enclosed by these Fermi surfaces to <Q>. We survey models of interacting bosons and/or fermions and/or gauge fields which realize such phases. Some phases have Fermi surfaces with the singularities of Landau's Fermi liquid theory, while other Fermi surfaces have non-Fermi liquid singularities. Compressible phases found in models applicable to condensed matter systems are argued to also be present in models obtained by applying chemical potentials (and other deformations allowed by the residual symmetry at non-zero chemical potential) to the paradigmic supersymmetric gauge theories underlying gauge-gravity duality: the ABJM model in spatial dimension d=2, and the N=4 SYM theory in d=3.
The compiled record
The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.
The abstract, sentence by sentence
We give a unified overview of the zero temperature phases of compressible quantum matter: i.e. phases in which the expectation value of a globally conserved U(1) density, Q, varies smoothly as a function of parameters. Provided the global U(1) and translational symmetries are unbroken, such phases are expected to have Fermi surfaces, and the Luttinger theorem relates the volumes enclosed by these Fermi surfaces to <Q>. We survey models of interacting bosons and/or fermions and/or gauge fields which realize such phases. Some phases have Fermi surfaces with the singularities of Landau's Fermi liquid theory, while other Fermi surfaces have non-Fermi liquid singularities. Compressible phases found in models applicable to condensed matter systems are argued to also be present in models obtained by applying chemical potentials (and other deformations allowed by the residual symmetry at non-zero chemical potential) to the paradigmic supersymmetric gauge theories underlying gauge-gravity duality: the ABJM model in spatial dimension d=2, and the N=4 SYM theory in d=3.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We give a unified overview of the zero temperature phases of compressible quantum matter: i.e. phases in which the expectation value of a globally conserved U(1) density, Q, varies smoothly as a function of parameters. | contribution 0.88 | 0.44 | 0.12 | asserted 0.92 |
| s1 | Provided the global U(1) and translational symmetries are unbroken, such phases are expected to have Fermi surfaces, and the Luttinger theorem relates the volumes enclosed by these Fermi surfaces to <Q>. | background 1.00 | 0.06 | 0.09 | hedged possibility 0.94 |
| s2 | We survey models of interacting bosons and/or fermions and/or gauge fields which realize such phases. | contribution 0.92 | 0.55 | 0.06 | asserted 0.76 |
| s3 | Some phases have Fermi surfaces with the singularities of Landau's Fermi liquid theory, while other Fermi surfaces have non-Fermi liquid singularities. | result 0.69 | 0.16 | 0.09 | asserted 0.97 |
| s4 | Compressible phases found in models applicable to condensed matter systems are argued to also be present in models obtained by applying chemical potentials (and other deformations allowed by the residual symmetry at non-zero chemical potential) to the paradigmic supersymmetric gauge theories underlying gauge-gravity duality: the ABJM model in spatial dimension d=2, and the N=4 SYM theory in d=3. | result 0.43 | 0.46 | 0.61 | hedged possibility 0.80 |
What was examined, and what was not
- arXiv listing abstract v2
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- P abstract
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Figures
Figures reproduced from arXiv:1104.5022 by the authors.
References
How later papers used it
65 later papers cite it
2 later papers by other authors are listed below: 1 compared its own results with it and 1 cited it as support.
Compares with it 1 of 4 papers with this label
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Said that the top-down model it obtained does not match perfectly that of this paper.
Nonrelativistic limit of the abelianized ABJM model and the ADS/CMT correspondence (2015) · 1.00 · paraphrased: the licence does not allow quoting
Cites it as support 1 of 3 papers with this label
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Presented its strongly coupled but fully calculable example as supporting this paper's conjecture that systems with a chemical potential for a global U(1) symmetry, with the symmetry and translations unbroken, have Fermi surfaces.
Emergent Fermi surfaces, fractionalization and duality in supersymmetric QED (2014) · 0.97 · paraphrased: the licence does not allow quoting
How the literature uses it
62 arXiv papers cite this in 116 sentences
Papers citing it · 75 sentences without a confident label
Builds on it 1 paper
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As an example, we can consider a CFT3 with Dirac fermions, such as those in [ref] , obtained by replacing $z_1, z_2$ in $ℒ_ℂℙ$ (Eq. ([ref])) by two-component Dirac fermions, $q_1, q_2$.
Compressible quantum phases from conformal field theories in 2+1 dimensions · Generalizations · 0.88
Uses its method or tool 1 paper
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One way to make the notion more precise is via the `Luttinger count' [ref] .
Horizons, holography and condensed matter · Horizons, fractionalization and black hole information · 0.81
Compares with it 4 papers
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The three phases that appear have important similarities with the FL, FL$^*$ and NFL phases discussed in [ref] .
Fractionalization of holographic Fermi surfaces · Context · 1.00
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With the truncation $A_μ^(1)=-A_μ^(2)=A_μ$ and recalling that the covariant derivative $D_μ= (_̣μ-iA_μ^(i))$ acting on both $ϕ_i$ and $ψ_i$, we obtain the action S = N(N-1)∫d^3x[kħ/4πϵ^μνρA_μF_νρ+f_+^†((_̣τ-iA_τ)-(∇⃗-iA⃗)^2/ 2m-F_12/2m)f_+. .+f_-^†((_̣τ+iA_τ)-(∇⃗+iA⃗)^2/ 2m+F_12/2m)f_- +b^†_+((_̣τ-iA_τ)-(∇⃗-iA⃗)^2/2m)b_+. +b^†_-((_̣τ+iA_τ)-(∇⃗+iA⃗)^2/2m)b_- -2πħ^2/mkb^†_+b^†_-b_+b_- .-πħ^2/km[b^†_+b_+f^†_-f_-+b^†_-b_-f^†_+f_+]], with an extra CS term, and where to facilitate comparison to ([ref]) we have denoted $ψ_1=f_+, ψ_2=f_-,ϕ_1=b_+,ϕ_2=b_-$ and changed to the conventions of [ref] .
Nonrelativistic limit of the abelianized ABJM model and the ADS/CMT correspondence · Comparison with nonrelativistic abelian toy models for ABJM · 1.00
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This behavior is reminiscent of various theoretical models based on a large spatial dimension mean field approximation [ref] , such as the gapless quantum liquids of [ref] and the “local quantum critical point” of [ref] [1]Some suggestions for a connection have been made in [ref] ..
Lectures on holographic non-Fermi liquids and quantum phase transitions · Semi-local quantum liquids · 0.86
Cites it as support 2 papers
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A Low temperature compressible state, in the absence of symmetry breaking, can be taken as indicative of a Fermi surface (see e.g. the discussion in [ref] ).
Compressible Matter at a Holographic Interface · Thermodynamics · 0.96
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It provides a strongly coupled but fully calculable example supporting the conjecture of [ref] that systems with a chemical potential for a global $U(1)$ symmetry, where the symmetry and translations are unbroken, have Fermi surfaces.
Emergent Fermi surfaces, fractionalization and duality in supersymmetric QED · Emergent Fermi surface in the magnetic description · 0.97
Cites it as background 24 papers
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A second class of compressible ground states of doped CFTs, known variously as `non-Fermi liquids', `strange metals' or `Bose metals', were proposed in [ref] using arguments mainly from the CFT side.
Compressible quantum phases from conformal field theories in 2+1 dimensions · Introduction · 0.91
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A discussion in the context of the gauge-gravity duality appears in a recent paper [ref] .
The landscape of the Hubbard model · The Metal-insulator transition on the triangular lattice · 0.97
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From a condensed matter perspective, a key issue in the zero temperature theory of any metallic state is the fate of the Luttinger relation [ref] , equating the total charge density, $𝒬$ to the volumes enclosed by the Fermi surfaces.
Hidden Fermi surfaces in compressible states of gauge-gravity duality · Introduction · 0.95
What it cites · 116 sentences without a confident label
Uses the method or tool of 2 papers
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We therefore make the following mode expansion [ref] in terms of canonical Fermi operators $a_i^a (k)$ and $b_i^a (k)$ λ_i^a (x) = ∫d^3k/(2 π)^3 ( [ - sin( θ_k/2) e^-i ϕ_k; cos( θ_k/2) ] ) [ a_i^a (k) e^- i k ·x + b_i^a † (k) e^ i k ·x ], where $θ_k$ and $ϕ_k$ are the polar and azimuthal angles of $k$, so under $k →- k$, $θ→π- θ$ and $ϕ→ϕ+ π$.
Color-Flavor Locking and Chiral Symmetry Breaking in High Density QCD · Lagrangian for $𝒩=4$ Super Yang-Mills theory · 0.90
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Now it is useful to introduce a fermionic `molecular' field $c_σ$ by a Hubbard-Stratonovich decoupling [ref] of the two-body interaction: ℒ_bf = f_σ^†[ ∂_τ- ∇^2/2 m_f - μ] f_σ+ b^†[ ∂_τ- ∇^2/2 m_b - μ_b ] b + u/2 (b^† b )^2 + 1/g c_σ^†c_σ- c_σ^†b f - f^†b^†c_σ.
Sum Rules and Ward Identities in the Kondo Lattice · Boson-fermion mixture · 0.99
Compares with 4 papers
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Instead, the boson and gauge sector of $ℒ_0$ is closely related to theories of doped antiferromagnets [ref] in which the global charge is carried by the bosons, and the spin is carried by the fermions.
Competing orders II: the doped quantum dimer model · Theory similar to the ABJM model in $d=2$ · 0.83
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Instead, the boson and gauge sector of $ℒ_0$ is closely related to theories of doped antiferromagnets [ref] in which the global charge is carried by the bosons, and the spin is carried by the fermions.
Doping a Mott Insulator: Physics of High Temperature Superconductivity · Theory similar to the ABJM model in $d=2$ · 0.83
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Instead, the boson and gauge sector of $ℒ_0$ is closely related to theories of doped antiferromagnets [ref] in which the global charge is carried by the bosons, and the spin is carried by the fermions.
Dual vortex theory of doped Mott insulators · Theory similar to the ABJM model in $d=2$ · 0.83
Cites as background 7 papers
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[ref] This gauge theory has $𝒩=6$ supersymmetry along with a global SU(4) symmetry.
N=6 superconformal Chern-Simons-matter theories, M2-branes and their gravity duals · Theory similar to the ABJM model in $d=2$ · 0.85
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The fractionalized Fermi liquid (FL*) was introduced in Refs. [ref] as a compressible non-Fermi liquid phase of Kondo and Hubbard lattice models of strongly interacting electrons.
Weak magnetism and non-Fermi liquids near heavy-fermion critical points · Fractionalized Fermi liquid · 0.89
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The fractionalized Fermi liquid (FL*) was introduced in Refs. [ref] as a compressible non-Fermi liquid phase of Kondo and Hubbard lattice models of strongly interacting electrons.
Fractionalized Fermi liquids · Fractionalized Fermi liquid · 0.89
Discussion
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