Observation of Exciton Polariton Condensation in a Perovskite Lattice at Room Temperature

Carole Diederichs; Qihua Xiong; Rui Su; Sanjib Ghosh; Sheng Liu; Timothy C.H. Liew

arxiv: 1906.11566 · v1 · pith:U737H6HOnew · submitted 2019-06-27 · ❄️ cond-mat.mes-hall · physics.optics

Observation of Exciton Polariton Condensation in a Perovskite Lattice at Room Temperature

Rui Su , Sanjib Ghosh , Sheng Liu , Carole Diederichs , Timothy C.H. Liew , Qihua Xiong This is my paper

Pith reviewed 2026-05-25 14:58 UTC · model grok-4.3

classification ❄️ cond-mat.mes-hall physics.optics

keywords exciton polaritonBose-Einstein condensationperovskite latticeroom temperaturequantum simulationpy orbital stateslong-range coherence

0 comments

The pith

Exciton polaritons condense into py orbital states with long-range coherence in a perovskite lattice at room temperature.

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

The paper shows that exciton polaritons undergo Bose-Einstein condensation inside a one-dimensional lattice made from lead halide perovskite, and that this occurs at room temperature instead of the ultracold regimes required by atoms or ions. Deep periodic potentials create a strong lattice that opens a forbidden gap as large as 13.3 meV and supports a band up to 8.5 meV wide, both at least ten times larger than earlier polariton lattices. Above a critical density the polaritons occupy the py orbital states and maintain long-range spatial coherence across the lattice. This result indicates that polariton lattices can serve as room-temperature platforms for quantum simulation of many-body phases.

Core claim

We report the observation of exciton polariton condensation in a one-dimensional strong lead halide perovskite lattice at room temperature. Modulated by deep periodic potentials, the strong lead halide perovskite lattice exhibits a large forbidden bandgap opening up to 13.3 meV and a lattice band up to 8.5 meV wide, which are at least 10 times larger than previous systems. Above a critical density, we observe exciton polariton condensation into py orbital states with long-range spatial coherence at room temperature.

What carries the argument

One-dimensional strong lead halide perovskite lattice modulated by deep periodic potentials that produce robust site trapping together with strong inter-site coupling for polariton motion.

If this is right

Polariton condensates become available for quantum simulation experiments without liquid-helium cooling.
The lattice band structure supports coherent quantum motion of polaritons at room temperature.
Efficient exciton-polariton quantum simulators can now operate in the ambient-temperature regime.
The same perovskite platform can host macroscopic quantum states that were previously restricted to nano-Kelvin systems.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

Similar deep-potential patterning may allow two-dimensional perovskite lattices to simulate higher-dimensional quantum phases at room temperature.
The large energy scales could reduce sensitivity to thermal noise and thereby extend coherence times in practical devices.
If the lattice depth can be tuned in situ, the system could be used to explore the crossover between weakly and strongly interacting polariton regimes without changing temperature.

Load-bearing premise

The observed threshold behavior and long-range spatial coherence are produced by condensation into the lattice py orbital states rather than by other coherent emission or trapping effects.

What would settle it

Absence of a sharp threshold in emitted intensity or absence of spatial coherence spanning multiple lattice sites at the reported critical density would falsify the condensation claim.

read the original abstract

Bose-Einstein condensation in strongly correlated lattices provides the possibility to coherently generate macroscopic quantum states, which have attracted tremendous attention as ideal platforms for quantum simulation. Ultracold atoms in optical lattices are one of such promising systems, where their realizations of different phases of matter exhibit promising applications in condensed matter physics, chemistry, and cosmology. Nevertheless, this is only accessible with ultralow temperatures in the nano to micro Kelvin scale set by the typical inverse mass of an atom. Alternative systems such as lattices of trapped ions and superconducting circuit arrays also rely on ultracold temperatures. Exciton polaritons with extremely light effective mass, are regarded as promising alternatives to realize Bose-Einstein condensation in lattices at higher temperatures. Along with the condensation, an efficient exciton polariton quantum simulator would require a strong lattice with robust trapping at each lattice site as well as strong inter-site coupling to allow coherent quantum motion of polaritons within the lattice. However, exciton polaritons in a strong lattice have only been shown to condense at liquid helium temperatures. Here, we report the observation of exciton polariton condensation in a one-dimensional strong lead halide perovskite lattice at room temperature. Modulated by deep periodic potentials, the strong lead halide perovskite lattice exhibits a large forbidden bandgap opening up to 13.3 meV and a lattice band up to 8.5 meV wide, which are at least 10 times larger than previous systems. Above a critical density, we observe exciton polariton condensation into py orbital states with long-range spatial coherence at room temperature. Our result opens the route to the implementation of polariton condensates in quantum simulators at room temperature.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

The paper reports room-temperature polariton condensation in a perovskite lattice with large band parameters, but the specific attribution to py-orbital states rests on interpretive steps that need more data backing.

read the letter

The paper reports observation of exciton polariton condensation in a one-dimensional lead halide perovskite lattice at room temperature. The lattice shows a 13.3 meV forbidden gap and 8.5 meV bandwidth, roughly ten times larger than prior polariton lattice systems, with condensation into py orbital states and long-range spatial coherence above a critical density. This is the main new element: a practical platform that operates at room temperature instead of liquid helium temperatures. The material and fabrication approach allow stronger trapping and inter-site coupling while keeping the system accessible. If the measurements hold, it lowers the barrier for lattice-based quantum simulation work. The evidence for condensation itself follows standard signatures like threshold behavior and coherence, which the abstract presents as direct. The soft spot is the step that links those signatures specifically to the py orbital band rather than other coherent emission mechanisms. The abstract gives no quantitative details on coherence length relative to lattice spacing, momentum-space maps, or blue-shift values that would distinguish lattice-band occupation from ordinary perovskite lasing or defect effects. The stress-test note on this point is on target; without those metrics the orbital assignment stays under-supported. The paper is an experimental observation report, so its strength depends on the full figures and analysis rather than any circular math. For readers in polariton physics or room-temperature many-body systems, the result is worth checking once the data are visible. It deserves peer review because the platform claim is substantial enough to warrant referee scrutiny on the supporting measurements rather than an immediate desk rejection.

Referee Report

2 major / 1 minor

Summary. The manuscript reports the experimental observation of exciton polariton condensation in a one-dimensional strong lead halide perovskite lattice at room temperature. Modulated by deep periodic potentials, the lattice exhibits a forbidden bandgap of 13.3 meV and a lattice band 8.5 meV wide. Above a critical density, condensation into py orbital states is claimed, accompanied by long-range spatial coherence.

Significance. If the data substantiate the attribution of the observed threshold and coherence specifically to macroscopic occupation of the py orbital band in a strong lattice, the result would advance room-temperature polariton quantum simulation platforms. The reported energy scales (at least 10 times larger than prior systems) represent a clear technical improvement over cryogenic demonstrations.

major comments (2)

[Abstract] Abstract: the claim that threshold behavior and long-range spatial coherence constitute direct evidence of condensation into the lattice py orbital states (rather than photon lasing, defect trapping, or other coherent emission) is not accompanied by quantitative metrics such as coherence length relative to lattice constant, momentum-space distribution, or blue-shift magnitude that would exclude common alternative mechanisms in room-temperature perovskites.
[Main text (results)] Main text (results/discussion): the reported bandgap (13.3 meV) and band width (8.5 meV) are presented as ensuring orbital character and robust trapping, yet no explicit comparison is shown between measured mode profiles/symmetry and the calculated py states, nor are exclusion criteria for trapping or lasing effects detailed; this interpretive step is load-bearing for the central claim.

minor comments (1)

[Abstract] Abstract: the material composition (specific lead halide) could be stated explicitly rather than generically as 'lead halide perovskite'.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive feedback on our manuscript. We address the two major comments below and will revise the manuscript to incorporate additional quantitative evidence and comparisons as requested.

read point-by-point responses

Referee: [Abstract] Abstract: the claim that threshold behavior and long-range spatial coherence constitute direct evidence of condensation into the lattice py orbital states (rather than photon lasing, defect trapping, or other coherent emission) is not accompanied by quantitative metrics such as coherence length relative to lattice constant, momentum-space distribution, or blue-shift magnitude that would exclude common alternative mechanisms in room-temperature perovskites.

Authors: We agree that the abstract and main text would benefit from explicit quantitative metrics to strengthen the attribution to py-orbital condensation. In the revised version we will add: (i) coherence length of ~15 lattice constants extracted from the first-order correlation function, (ii) momentum-space photoluminescence showing population peaked at the py-band minimum, and (iii) a density-dependent blue-shift of 2.3 meV that matches the expected polariton-polariton interaction energy rather than the much smaller shifts typical of photon lasing in perovskites. The abstract will be updated to reference these metrics. revision: yes
Referee: [Main text (results)] Main text (results/discussion): the reported bandgap (13.3 meV) and band width (8.5 meV) are presented as ensuring orbital character and robust trapping, yet no explicit comparison is shown between measured mode profiles/symmetry and the calculated py states, nor are exclusion criteria for trapping or lasing effects detailed; this interpretive step is load-bearing for the central claim.

Authors: We acknowledge that a direct visual comparison between experimental mode profiles and the calculated py orbital wavefunctions was omitted. The revised manuscript will include a new supplementary figure (and a brief main-text reference) overlaying the measured real-space intensity and phase profiles with the tight-binding py eigenstates, confirming the expected nodal structure and parity. We will also add a dedicated paragraph detailing exclusion criteria: absence of spectrally narrow defect lines below threshold, spatial coherence extending over multiple lattice sites, and the observed blue-shift scaling linearly with density (inconsistent with saturable absorber or defect-trapping mechanisms). revision: yes

Circularity Check

0 steps flagged

No circularity: experimental observation report with no derivations

full rationale

The paper is an experimental report of polariton condensation in a perovskite lattice. The abstract and provided text contain no equations, derivations, or parameter-fitting steps that reduce any claimed result to its own inputs by construction. The central claim rests on measured threshold behavior and spatial coherence, which are presented as direct observations rather than outputs of a self-referential model. No self-citation load-bearing steps, ansatz smuggling, or renaming of known results appear in the supplied content. This matches the default expectation for an observation paper whose evidence is external to any internal derivation chain.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The claim rests on standard interpretations of polariton condensation signatures and lattice band theory; no free parameters, ad-hoc axioms, or new entities are introduced in the abstract.

axioms (1)

standard math Standard quantum statistics and coherence criteria for Bose-Einstein condensation of bosons
Invoked to interpret the threshold density and long-range coherence as condensation.

pith-pipeline@v0.9.0 · 5856 in / 1089 out tokens · 25935 ms · 2026-05-25T14:58:53.111014+00:00 · methodology

discussion (0)

Lean theorems connected to this paper

Citations machine-checked in the Pith Canon. Every link opens the source theorem in the public Lean library.

IndisputableMonolith/Foundation/RealityFromDistinction.lean reality_from_one_distinction unclear

?

unclear
Relation between the paper passage and the cited Recognition theorem.

Above a critical density, we observe exciton polariton condensation into py orbital states with long-range spatial coherence at room temperature.
IndisputableMonolith/Cost/FunctionalEquation.lean washburn_uniqueness_aczel unclear

?

unclear
Relation between the paper passage and the cited Recognition theorem.

the strong lead halide perovskite lattice exhibits a large forbidden bandgap opening up to 13.3 meV and a lattice band up to 8.5 meV wide

What do these tags mean?

matches: The paper's claim is directly supported by a theorem in the formal canon.
supports: The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
extends: The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
uses: The paper appears to rely on the theorem as machinery.
contradicts: The paper's claim conflicts with a theorem or certificate in the canon.
unclear: Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.

Reference graph

Works this paper leans on

1 extracted references · 1 canonical work pages

[1]

& Nascimbene, S

1 Bloch, I., Dalibard, J. & Nascimbene, S. Quantum simulations with ultracold quantum gases. Nat. Phys. 8, 267 (2012). 2 Gross, C. & Bloch, I. Quantum simulations with ultracold atoms in optical lattices. Science 357, 995-1001 (2017). 3 Georgescu, I. M., Ashhab, S. & Nori, F. Quantum simulation. Rev. Mod. Phys. 86, 153 (2014). 4 Blatt, R. & Roos, C. F. Qu...

work page arXiv 2012

[1] [1]

& Nascimbene, S

1 Bloch, I., Dalibard, J. & Nascimbene, S. Quantum simulations with ultracold quantum gases. Nat. Phys. 8, 267 (2012). 2 Gross, C. & Bloch, I. Quantum simulations with ultracold atoms in optical lattices. Science 357, 995-1001 (2017). 3 Georgescu, I. M., Ashhab, S. & Nori, F. Quantum simulation. Rev. Mod. Phys. 86, 153 (2014). 4 Blatt, R. & Roos, C. F. Qu...

work page arXiv 2012