arxiv: 2605.03876 · v1 · submitted 2026-05-05 · ❄️ cond-mat.mes-hall

Recognition: unknown

Remote entropy measurement in coupled quantum dots

Owen Sheekey , Tim Child , Elena Cornick , Saeed Fallahi , Geoffrey C. Gardner , Michael J. Manfra , Eran Sela , Yaakov Kleeorin

show 3 more authors

Yigal Meir Silvia L\"uscher Joshua Folk

Authors on Pith no claims yet

Pith reviewed 2026-05-07 14:25 UTC · model grok-4.3

classification ❄️ cond-mat.mes-hall

keywords quantum dotsentropy measurementMaxwell relationscapacitive couplingthermodynamicsmesoscopic physicsGaAs heterostructures

0 comments

The pith

Charge measurements on one quantum dot capture entropy changes in a coupled pair.

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

The paper establishes that Maxwell relation measurements of charge on a single quantum dot can extract the entropy change of an entire two-dot system rather than just the added electron. This remote probing works both when dots couple weakly to reservoirs, allowing direct microstate counting, and when coupling is stronger, requiring numerical renormalization group methods. A sympathetic reader cares because the technique lets researchers access more complex entropies in multi-particle systems without directly interrogating every component. Experiments on GaAs dots confirm the result across the two regimes.

Core claim

Using a pair of capacitively coupled GaAs quantum dots, charge measurements on one dot reveal entropy changes associated with the entire two-dot system, both at weak dot-reservoir coupling where microstate counting applies and at stronger coupling where numerical renormalization group calculations are required. Maxwell relation-based measurements therefore probe not only the entropy change associated with the added electron but also that of the surrounding system as it responds.

What carries the argument

Maxwell relation extraction of entropy from charge sensing on one member of a capacitively coupled quantum-dot pair

If this is right

Entropy changes of the full two-dot system become accessible through remote charge measurements.
The method remains valid in the weak-coupling regime using simple microstate counting.
Numerical renormalization group calculations correctly describe the entropy extraction at stronger couplings.
Exotic entropies in coupled quantum systems can be measured without direct access to every dot.

Where Pith is reading between the lines

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

The approach could scale to larger dot arrays for measuring collective or correlated entropies.
Varying capacitive coupling strength offers a direct experimental test of the remote-sensing limit.
Similar Maxwell-relation remote measurements may apply to graphene or other two-dimensional dot systems.
The technique provides a route to infer entanglement-related entropy contributions in multi-dot devices.

Load-bearing premise

Capacitive coupling transmits the full thermodynamic response of the two-dot system without corrections from residual tunneling, gate-induced potentials, or non-equilibrium effects.

What would settle it

A mismatch between the entropy extracted from one dot's charge response and the independently computed total entropy of the two-dot system when inter-dot tunneling or non-equilibrium conditions are deliberately increased.

Figures

Figures reproduced from arXiv: 2605.03876 by Elena Cornick, Eran Sela, Geoffrey C. Gardner, Joshua Folk, Michael J. Manfra, Owen Sheekey, Saeed Fallahi, Silvia L\"uscher, Tim Child, Yaakov Kleeorin, Yigal Meir.

**Figure 1.** Figure 1: FIG. 1. a) A false colour scanning electron micrograph of the view at source ↗

**Figure 3.** Figure 3: FIG. 3. a) Peak (black) and final (red) measurements of view at source ↗

**Figure 4.** Figure 4: explores the entropy change, ∆S(V˜D), across the (0, 1)–(1, 0) transition for the most strongly-coupled device setting in Fig. 3b. The data are collected midway between the triple points, as far as possible from the gate voltage settings where single-dot transitions are allowed. In our capacitively-coupled geometry, the (0, 1)–(1, 0) degeneracy cannot be lifted by direct interdot tunneling, but is instead… view at source ↗

read the original abstract

Recent experiments have demonstrated that measurements of the entropy change associated with the addition of electrons to semiconductor- and graphene-based quantum dots accurately quantify the spin and orbital degeneracy of the states into which they are added. However, measuring more exotic entropies requires probing the entropy change of an entire system in response to an added particle. Here, we demonstrate that Maxwell relation-based measurements probe not only the entropy change associated with the added electron but also that of the surrounding system as it responds to that electron. Using a pair of capacitively coupled GaAs quantum dots, we show that charge measurements on one dot reveal entropy changes associated with the entire two-dot system, both at weak dot--reservoir coupling where microstate counting applies and at stronger coupling where numerical renormalization group calculations are required.

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

Charge sensing on one dot extracts entropy changes for the full coupled pair via Maxwell relations, working in both microstate and NRG regimes.

read the letter

The main thing to know is that charge measurements on one quantum dot can capture entropy shifts in the entire two-dot system, not just the local addition, because the Maxwell relation ties the charge response to the full thermodynamic change under capacitive coupling. They demonstrate this from the weak-coupling limit where you just count microstates up to stronger coupling where NRG is needed for the interacting case. That separation of regimes is useful and avoids forcing a single model across the board. The approach builds directly on prior single-dot entropy work but extends it remotely without needing simultaneous probes on both dots. The setup looks consistent on paper: they use independent NRG calculations rather than fitting the same data to itself, so no obvious circularity. The experimental claim rests on real charge sensing data, which is a concrete step beyond theory. Soft spots are the usual ones for this kind of mesoscopic experiment. Without the full figures, error bars, or sample specifics it is hard to judge how well residual tunneling or gate effects were controlled, and the calibration of coupling strength could hide small corrections to the Maxwell extraction. Those are not fatal but they matter for how cleanly the remote signal transmits the full entropy. The paper is aimed at people working on quantum dot thermodynamics and entropy in few-electron systems; anyone trying to characterize multi-particle states or needing a practical probe would find the method worth trying. It is grounded enough and the central result is new enough that it should go to peer review rather than a desk reject.

Referee Report

0 major / 2 minor

Summary. The manuscript demonstrates remote entropy measurement in a pair of capacitively coupled GaAs quantum dots. Charge sensing on one dot, combined with Maxwell relations, extracts the entropy change of the full two-dot system. This is shown to hold both in the weak dot-reservoir coupling regime (where entropy is obtained from microstate counting) and at stronger coupling (where NRG calculations are required for comparison).

Significance. If the central claim holds, the work provides a practical route to measure system-wide entropy responses without direct access to all components, extending prior single-dot degeneracy counting to capacitively coupled structures. The dual validation against both analytic counting and NRG strengthens the case that capacitive coupling faithfully transmits the thermodynamic response, which may enable future studies of exotic entropies in more complex mesoscopic devices.

minor comments (2)

The abstract and introduction would benefit from a brief quantitative statement of the achieved coupling strengths (e.g., the ratio of inter-dot capacitance to total capacitance) to allow readers to assess the crossover between the two regimes without consulting the figures.
Figure captions should explicitly state the temperature range and the number of independent cooldowns or devices used for the data sets shown, to clarify the statistical robustness of the entropy extraction.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for their positive summary of our manuscript on remote entropy measurement in capacitively coupled GaAs quantum dots and for recommending minor revision. No specific major comments are provided in the report, so we have no individual points to address point-by-point. We will incorporate any minor changes needed in the revised version.

Circularity Check

0 steps flagged

No significant circularity

full rationale

The paper's central demonstration relies on established Maxwell relations applied to charge sensing in capacitively coupled dots, combined with independent microstate counting for weak coupling and NRG calculations for stronger coupling. No load-bearing step reduces by construction to a fitted parameter or self-referential definition from the same dataset; the thermodynamic extraction is externally grounded and the regimes are treated with standard methods that do not loop back to the experimental inputs.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The central claim rests on the applicability of Maxwell relations to the coupled-dot thermodynamics and on the assumption that capacitive coupling is the dominant interaction; no free parameters or invented entities are introduced in the abstract.

axioms (1)

domain assumption Maxwell relations connect measurable charge response to entropy changes in the thermodynamic potential of the two-dot system
Invoked to justify that charge measurements on one dot capture the full-system entropy.

pith-pipeline@v0.9.0 · 5464 in / 1232 out tokens · 52074 ms · 2026-05-07T14:25:20.593173+00:00 · methodology

discussion (0)

Reference graph

Works this paper leans on

26 extracted references · 5 canonical work pages

[1]

Detect- ing the universal fractional entropy of Majorana zero modes,

Eran Sela, Yuval Oreg, Stephan Plugge, Nikolaus Hartman, Silvia L¨ uscher, and Joshua Folk, “Detect- ing the universal fractional entropy of Majorana zero modes,” arXiv (2019), 10.1103/physrevlett.123.147702, 1905.12237

work page doi:10.1103/physrevlett.123.147702 2019
[2]

Detecting Non-Abelian Anyons by Charging Spectroscopy,

G. Ben-Shach, C. R. Laumann, I. Neder, A. Yacoby, and B. I. Halperin, “Detecting Non-Abelian Anyons by Charging Spectroscopy,” Physical Review Letters110, 106805 (2013), 1212.1163

work page arXiv 2013
[3]

Observable Bulk Signa- tures of Non-Abelian Quantum Hall States,

N R Cooper and Ady Stern, “Observable Bulk Signa- tures of Non-Abelian Quantum Hall States,” Physical Review Letters (2008), 10.1103/physrevlett.102.176807, 0812.3387

work page doi:10.1103/physrevlett.102.176807 2008
[4]

Mea- suring topological entanglement entropy using maxwell relations,

Sarath Sankar, Eran Sela, and Cheolhee Han, “Mea- suring topological entanglement entropy using maxwell relations,” Physical Review Letters131, 016601 (2023)

2023
[5]

Entropic evidence for a Pomeranchuk effect in magic-angle graphene,

Asaf Rozen, Jeong Min Park, Uri Zondiner, Yuan Cao, Daniel Rodan-Legrain, Takashi Taniguchi, Kenji Watan- abe, Yuval Oreg, Ady Stern, Erez Berg, Pablo Jarillo- Herrero, and Shahal Ilani, “Entropic evidence for a Pomeranchuk effect in magic-angle graphene,” Nature 592, 214–219 (2021), 2009.01836

work page arXiv 2021
[6]

Isospin pomeranchuk effect in twisted bilayer graphene,

Yu Saito, Fangyuan Yang, Jingyuan Ge, Xiaoxue Liu, Takashi Taniguchi, Kenji Watanabe, JIA Li, Erez Berg, and Andrea F Young, “Isospin pomeranchuk effect in twisted bilayer graphene,” Nature592, 220–224 (2021)

2021
[7]

Direct entropy measurement in a mesoscopic quantum system,

Nikolaus Hartman, Christian Olsen, Silvia L¨ uscher, Mo- hammad Samani, Saeed Fallahi, Geoffrey C. Gardner, Michael Manfra, and Joshua Folk, “Direct entropy measurement in a mesoscopic quantum system,” Nature Physics14, 1083–1086 (2018), 1905.12388

work page arXiv 2018
[8]

A robust protocol for entropy measurement in mesoscopic circuits,

Timothy Child, Owen Sheekey, Silvia L¨ uscher, Saeed Fal- lahi, Geoffrey C Gardner, Michael Manfra, and Joshua Folk, “A robust protocol for entropy measurement in mesoscopic circuits,” Entropy24, 417 (2022)

2022
[9]

Entropy measurement of a strongly coupled quantum dot,

Timothy Child, Owen Sheekey, Silvia L¨ uscher, Saeed Fallahi, Geoffrey C Gardner, Michael Manfra, Andrew Mitchell, Eran Sela, Yaakov Kleeorin, Yigal Meir,et al., “Entropy measurement of a strongly coupled quantum dot,” Physical Review Letters129, 227702 (2022)

2022
[10]

Entropy spectroscopy of a bilayer graphene quantum dot,

C. Adam, H. Duprez, N. Lehmann, A. Yglesias, A. O. Denisov, S. Cances, M. J. Ruckriegel, M. Masseroni, C. Tong, W. Huang, D. Kealhofer, R. Garreis, K. Watan- abe, T. Taniguchi, K. Ensslin, and T. Ihn, “Entropy spectroscopy of a bilayer graphene quantum dot,” Phys. Rev. Lett.135, 126202 (2025)

2025
[11]

Entropy of a double quantum dot,

David Kealhofer, Christoph Adam, Max J. Ruckriegel, Petar Tomi´ c, Benedikt Kratochwil, Christian Reichl, Yi- gal Meir, Werner Wegscheider, Thomas Ihn, and Klaus Ensslin, “Entropy of a double quantum dot,” Phys. Rev. Lett.135, 206303 (2025)

2025
[12]

Complete mapping of the thermoelectric properties of a single molecule,

Pascal Gehring, Jakub K Sowa, Chunwei Hsu, Joeri de Bruijckere, Martijn van der Star, Jennifer J Le Roy, Lapo Bogani, Erik M Gauger, and Herre SJ van der Zant, “Complete mapping of the thermoelectric properties of a single molecule,” Nature nanotechnology16, 426–430 (2021)

2021
[13]

Controlling the en- tropy of a single-molecule junction,

Eugenia Pyurbeeva, Chunwei Hsu, David Vogel, Christina Wegeberg, Marcel Mayor, Herre Van Der Zant, Jan A Mol, and Pascal Gehring, “Controlling the en- tropy of a single-molecule junction,” Nano Letters21, 9715–9719 (2021)

2021
[14]

Strongly capacitively coupled quantum dots,

Ian H Chan, RM Westervelt, KD Maranowski, and AC Gossard, “Strongly capacitively coupled quantum dots,” Applied Physics Letters80, 1818–1820 (2002)

2002
[15]

Two laterally arranged quantum dot systems with strong ca- pacitive interdot coupling,

A H¨ ubel, J Weis, W Dietsche, and K v Klitzing, “Two laterally arranged quantum dot systems with strong ca- pacitive interdot coupling,” Applied Physics Letters91 (2007)

2007
[16]

Corre- lated electron tunneling through two separate quantum dot systems with strong capacitive interdot coupling,

A. H¨ ubel, K. Held, J. Weis, and K. v. Klitzing, “Corre- lated electron tunneling through two separate quantum dot systems with strong capacitive interdot coupling,” Phys. Rev. Lett.101, 186804 (2008)

2008
[17]

Su (4) fermi liquid state and spin filtering in a double quantum dot system,

L´ aszl´ o Borda, Gergely Zar´ and, Walter Hofstetter, BI Halperin, and Jan von Delft, “Su (4) fermi liquid state and spin filtering in a double quantum dot system,” Physical review letters90, 026602 (2003)

2003
[18]

Quantum phase transition in capacitively cou- pled double quantum dots,

Martin R Galpin, David E Logan, and HR Krishna- murthy, “Quantum phase transition in capacitively cou- pled double quantum dots,” Physical review letters94, 186406 (2005)

2005
[19]

Gate voltage effects in capacitively coupled quan- tum dots,

Andrew K Mitchell, Martin R Galpin, and David E Lo- gan, “Gate voltage effects in capacitively coupled quan- tum dots,” Europhysics Letters76, 95 (2006)

2006
[20]

Spin- orbital kondo effect in a parallel double quantum dot,

Yuma Okazaki, Satoshi Sasaki, and Koji Muraki, “Spin- orbital kondo effect in a parallel double quantum dot,” Phys. Rev. B84, 161305 (2011)

2011
[21]

Capacitively coupled double quantum dot system in the kondo regime,

Irisnei L Ferreira, PA Orellana, GB Martins, FM Souza, and E Vernek, “Capacitively coupled double quantum dot system in the kondo regime,” Physical Review B—Condensed Matter and Materials Physics84, 205320 (2011)

2011
[22]

Pseudospin-resolved transport spectroscopy of the kondo effect in a double quantum dot,

S. Amasha, A. J. Keller, I. G. Rau, A. Carmi, J. A. Katine, Hadas Shtrikman, Y. Oreg, and D. Goldhaber- Gordon, “Pseudospin-resolved transport spectroscopy of the kondo effect in a double quantum dot,” Phys. Rev. Lett.110, 046604 (2013)

2013
[23]

Emergent su (4) kondo physics in a spin–charge-entangled double quantum dot,

AJ Keller, S Amasha, Ireneusz Weymann, CP Moca, IG Rau, JA Katine, Hadas Shtrikman, G Zar´ and, and D Goldhaber-Gordon, “Emergent su (4) kondo physics in a spin–charge-entangled double quantum dot,” Nature Physics10, 145–150 (2014)

2014
[24]

Spin-orbital and spin kondo effects in parallel coupled quantum dots,

D Krychowski and S Lipi´ nski, “Spin-orbital and spin kondo effects in parallel coupled quantum dots,” Phys- ical Review B93, 075416 (2016)

2016
[25]

Many-body tunneling and nonequilibrium dynamics in double quantum dots with capacitive coupling,

Wenjie Hou, Yuandong Wang, Weisheng Zhao, Zhen- gang Zhu, Jianhua Wei, Honggang Luo, and Yijing Yan, “Many-body tunneling and nonequilibrium dynamics in double quantum dots with capacitive coupling,” Journal of Physics: Condensed Matter33, 075301 (2020)

2020
[26]

Kondo-assisted switching between three conduction states in capacitively coupled quantum dots,

Pierre Lombardo, Roland Hayn, Denis Zhuravel, and Steffen Sch¨ afer, “Kondo-assisted switching between three conduction states in capacitively coupled quantum dots,” Physical Review Research2, 033387 (2020). 6 SUPPLEMENT AR Y INFORMA TION S1. T echnical notes on data acquisition Gate voltages and heater bias currents were set by DACs operating at a sampli...

2020