Vertically Coupled Double Quantum Dots Connected In Parallel

Seigo Tarucha; Shinichi Amaha; Takashi Nakajima; Tsuyoshi Hatano

REVIEW 4 major objections 5 minor 1 cited by

Vertically Coupled Double Quantum Dots Connected In Parallel

T0 review · 4 major / 5 minor · reviewed 2026-08-06 · deepseek-v4-flash

Challenge this review Re-run · record.json Download PDF Read on arXiv ↗ Review JSON

Pith's one-line read A four-dot ring built from two stacked double-dot pairs reveals its interlayer energy offsets ($\Delta_R \approx U/2$, $\Delta_L \approx 3U/2$) through Coulomb-diamond kinks and vertical lines, identifying the device as a platform for…

desk verdict A real device paper with a new four-dot ring geometry and a sensible offset-extraction method, but the headline Delta values are uncalibrated fit outputs and the lattice proposals are forward-looking, not results. read the letter →

arxiv 2507.09598 v1 pith:2RZZWSEB submitted 2025-07-13 cond-mat.mes-hall

Shinichi Amaha , Tsuyoshi Hatano , Takashi Nakajima , Seigo Tarucha This is my paper · ORCID

classification cond-mat.mes-hall PACS 73.21.La73.23.Hk

keywords quadruplequantumdotverticallycoupleddoubledotsCoulombdiamondspectroscopyinterlayerenergyoffsetconstantinteractionmodellayerisospinNagaokaferromagnetismartificialgraphene

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 reports a fabricated quadruple-quantum-dot ring made from two vertically coupled double quantum dots connected in parallel. It claims that Coulomb-diamond spectroscopy can read out the interlayer energy offset in each double-dot pair: about $\Delta_R \approx U/2$ for the right pair and $\Delta_L \approx 3U/2$ for the left pair, determined by matching constant-interaction model simulations to kinks and vertical lines in the diamond edges. If correct, the device is a four-site artificial lattice whose layer index acts as a tunable isospin, and the same platform can be extended to triangular and honeycomb arrays to search for isospin frustration and interaction-driven phases. The large measured offsets are also used to explain why the one-hole quarter-filled ring does not show Nagaoka ferromagnetism.

What carries the argument

The load-bearing object is the parallel-connected pair of vertically coupled double quantum dots, a four-dot ring in which each mesa contains an upper and a lower dot separated by a 5.5 nm barrier. The observable that carries the argument is the Coulomb diamond, measured along gate sweeps that deplete one double dot and therefore expose the other; within those diamonds, a kink and a vertical line mark the energy offset between the two layers. The matching is done with the constant-interaction (CI) model, which assigns fixed capacitances and a charging energy $U$ and reproduces the diamond boundaries. For the triangular extension, the derived effective isospin Hamiltonian $H_{\mathrm{eff}} = J_{\mathrm{eff}} \sum_{\langle i,j\rangle} I_i^z I_j^z + \Delta \sum_i I_i^z$ turns the layer index into a pseudospin-$1/2$ whose frustration depends on the ratio $\Delta/J_{\mathrm{eff}}$.

What would settle it

A direct test is to add an independent charge sensor or individual contacts that read the electron number in the upper and lower dot of each mesa during the same gate sweep: if the measured occupation sequence along the A-B and C-D lines disagrees with the CI-model label, or if the predicted kink position does not follow the model's gate-voltage dependence, the extracted offsets and the ring-coupling interpretation would be wrong.

Watch

Extended reading notes

Core claim

The central claim is that the fabricated structure behaves not as two independent vertical channels but as four quantum dots coupled in a ring, with vertical interlayer tunnel coupling $2t \sim 0.4\,\mathrm{meV}$ dominating the lateral coupling $2t \sim 0.2\,\mathrm{meV}$. Along gate trajectories that deplete one double dot, the remaining dot pair shows distorted Coulomb diamonds whose kinks and vertical boundary lines are reproduced by a constant-interaction model with an energy offset between the upper and lower dots; matching gives $\Delta_R \sim U/2$ and $\Delta_L \sim 3U/2$. With those offsets, the stability diagram can be labelled with definite charge configurations $(N_{RU}, N_{RD}, N_{LU}, N_{LD})$, including the three-electron state $(1,1,0,1)$ that would realize the Nagaoka filling if site energies were uniform. Because the offsets break site equivalence, the paper argues that the Nagaoka mechanism is suppressed, and it derives an effective isospin Hamiltonian for a triangular array, $H_{\mathrm{eff}} = J_{\mathrm{eff}} \sum_{\langle i,j\rangle} I_i^z I_j^z + \Delta \sum_i I_i^z$ with $J_{\mathrm{eff}} \sim 4t^2/(U-V)$, in which a small $\Delta$ preserves isospin frustration while a large $\Delta$ polarizes it away.

Load-bearing premise

The offset values are not measured directly; they are inferred by matching constant-interaction model simulations to the positions of kinks and vertical lines in the Coulomb diamonds, and the whole interpretation depends on those charge-state assignments being correct.

Editorial extensions

If this is right

The four-dot ring is a working artificial lattice in which the charge state can be fully labelled, including the three-electron configuration $(1,1,0,1)$ that sits at the Nagaoka filling.
The measured interlayer offsets mean the site energies are not uniform, so Pauli spin blockade and Nagaoka ferromagnetism should not be expected in this device as built; gate tuning or a different barrier design would be needed to restore site equivalence.
The same measurement protocol of depleting one double dot and mapping kinks and vertical lines gives a per-pair calibration of $\Delta$ for any larger array of vertically coupled dots.
In a triangular array, the effective Hamiltonian predicts that isospin frustration survives only when $\Delta$ is small compared with $J_{\mathrm{eff}} \approx 4t^2/(U-V)$, so the bias-spectroscopy measurement of $\Delta$ is the quantity that decides whether the frustrated phase is accessible.

Reading between the lines

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

If the offsets could be pushed toward zero by gate voltages, the same ring would become a direct testbed for an isospin analogue of Nagaoka ferromagnetism; the paper does not demonstrate this tuning, but its calibration procedure is exactly what such a test would need.
The large asymmetry between $\Delta_L \sim 3U/2$ and $\Delta_R \sim U/2$ suggests the two mesas differ electrostatically; a testable extension is to check whether the offset difference tracks lithographic or gate asymmetries, and whether a common gate bias can equalize it.
The effective Ising Hamiltonian neglects real spin, so a natural next step is to include spin and ask whether the $\Delta$-driven transition competes with spin ordering; the paper does not address that regime.
Because $J_{\mathrm{eff}}$ depends on $(U-V)$ in the denominator, the perturbative derivation is only valid for weak interlayer tunneling; a device with stronger vertical coupling would need a different analysis, and the measured diamonds would show avoided crossings that could calibrate $t$ directly.

Share X Bluesky LinkedIn Reddit HN

Signed reviews

No signed human review yet.

Editorial analysis

A structured set of objections, weighed in public.

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

Desk Editor's Note

read the letter

Short version: this is a real device paper, not a simulation stunt. The four-dot ring made from two vertically coupled DQDs connected in parallel is new relative to the parallel-coupled vertical DQD work they cite, and the bias spectroscopy along the A–B and C–D lines is a sensible way to get at the interlayer offsets of each DQD. The CI model reproduces the kink and vertical-line positions in Fig. 3, and the charge-state assignments in Fig. 4 are internally consistent. Credit where due: the device design is the contribution, and the extraction of Delta_R ~ U/2 and Delta_L ~ 3U/2 is the kind of parameter that matters for future isospin-lattice experiments. The paper cites the relevant prior work, including the source of t used later, and does not oversell the effective Hamiltonian as new.

Soft spots, in proportion. The two main quantitative claims are fit outputs. The paper does not report U, the lever arms, or the interdot capacitances used in the CI model, and gives no uncertainty on Delta_R or Delta_L. The stress-test note is right: with U not independently measured, the mapping from kinks/vertical lines to offset is underdetermined; you can move U and the offset together and keep a similar diamond shape. That does not make the numbers wrong, but it makes them unverified. The paper should either report the full parameter set and a stability analysis, or provide a second, independent estimate—the geometric relation between kink and vertical-line positions within a diamond is there for the taking. Also, the residual-current attribution to cotunneling is used to wave off one background, but the same cotunneling processes are a plausible alternative source for some of the marked features; the text should rule that out with data or with a calculation. No raw data or code are provided, which also makes the fit hard to check.

The ring topology claim is plausible but not proven. What the data show is lateral coupling between the two mesas plus the expected vertical coupling; a true four-dot ring with measurable next-neighbor coupling is an interpretation. The Nagaoka paragraph is appropriately hedged: they say the offsets suppress the state, not that they observed anything magnetic. The triangular/hexagonal sections are proposals, and the effective isospin Hamiltonian is standard second-order perturbation theory; the paper presents it as such, so no circularity problem.

Bottom line: this is a decent experimental contribution that deserves referee time, but it needs a revision that turns the offset extraction into a calibrated measurement. The audience is quantum-dot experimentalists interested in artificial lattices and isospin degrees of freedom. I would send it out, not desk-reject. My own verdict would be conditional, same as the reader's.

Referee Report

4 major / 5 minor

Summary. This manuscript reports differential-conductance measurements on a ring-shaped quadruple quantum dot formed by two vertically coupled double quantum dots connected in parallel. The authors observe honeycomb charge stability diagrams and distorted Coulomb diamonds, and use constant-interaction (CI) model simulations to assign charge configurations and estimate interlayer energy offsets, obtaining Delta_R ~ U/2 and Delta_L ~ 3U/2. They then argue that these offsets suppress the Nagaoka state at three-electron filling, and discuss extensions to triangular and hexagonal artificial lattices, including an effective isospin Hamiltonian with frustration.

Significance. If the offset extraction and ring-coupling assignment are reliable, the paper makes a modest but useful contribution: it demonstrates a geometry for accessing layer-isospin degrees of freedom in a four-dot ring and gives a concrete readout (kinks and vertical lines in Coulomb diamonds) for interlayer offsets. The authors are appropriately cautious in attributing residual current to cotunneling and in noting that finite offsets prevent Nagaoka ferromagnetism. The projected triangular-lattice Hamiltonian is a reasonable formal step, although it is not validated by data. The explicit use of a previously published interlayer tunneling parameter from Refs. [14,15] is a strength, because the central offset estimate is not obtained from a hidden fit to that same parameter.

major comments (4)

[2.1.2, Fig. 3] The offset values Delta_R~U/2 and Delta_L~3U/2 are obtained by visually matching CI-model simulations to the positions of one kink and one vertical line (Fig. 3(a,b)) and three kinks (Fig. 3(c,d)); the paper reports none of the model parameters (U, lever arms, capacitances), gives no uncertainty on the fitted offsets, and does not independently determine U. Because different combinations of U and offset can produce similar diamond shapes, the ratios Delta_R~U/2 and Delta_L~3U/2 are underdetermined as stated. I recommend either reporting a parameter scan showing the uniqueness of the fit, or extracting the offsets from the measured diamond geometry (e.g., from the bias and gate coordinates of the kink relative to the diamond edges) without relying on the fitted CI model.
[2.1.2, Fig. 3(b,d)] The CI model used here describes a serial DQD, and the text itself attributes the residual current in the nominally empty regime to cotunneling; these facts leave open the possibility that the marked kinks and vertical lines arise from level crossings, excited states, or cotunneling resonances rather than from a static interlayer offset. The charge-state assignments in Fig. 4, and hence the four-dot ring interpretation, depend on the claim that the CI model reproduces the features only with the quoted offsets. The authors should show that the features are absent in the zero-offset CI model for the same parameters and that no other parameter region reproduces them.
[3.1, Eq. (1)] The effective isospin Hamiltonian H_eff = J_eff sum I_i^z I_j^z + Delta sum I_i^z is asserted without derivation; the expression J_eff ~ 4t^2/(U-V) and the use of I^z as a bonding/antibonding isospin need a derivation or a supporting reference. The paper also does not state how V (interdot Coulomb energy) is defined relative to U, nor whether the assumed hierarchy t << U,V is consistent with the device parameters (2t~0.4 meV from Refs. [14,15], while U is not measured). Without these details, the frustration discussion in Sec. 3.1 is a proposal rather than a supported result.
[2.1.2, Fig. 4] The assignment of ring-like coupling in Fig. 4 rests on identifying charge states (1,1,0,0) and (0,1,0,1) as adjacent while the other DQD is depleted; however, no data are shown that directly resolve the electron numbers in both mesas simultaneously, and the stability diagram in Fig. 2 is interpreted through the serial-DQD CI model from Fig. 3. A transport signature of lateral coupling, such as an avoided crossing between the two DQD channels beyond the anti-crossings mentioned in Sec. 2.1.1, would strengthen the ring-topology claim.

minor comments (5)

[Fig. 1 caption] The sentence 'Note that two center gate electrodes are attached to the' is incomplete; please complete it or remove it.
[2.1, text] The text refers to 'gate voltages V_GL, V_GR, and V_GC applied to the gate electrodes G_L, G_R, and G_C', but the device has two center gates G_C1 and G_C2; the notation should be made consistent with Fig. 1(a).
[3.1, Eq. (1)] Define the notation <i,j> and I_i^z explicitly, and state whether the sum runs over nearest neighbors of the triangular lattice only.
[References] Reference [11] has an inconsistent author list ('M. Pi, A. Emperador, M. Barranco, F. Garcias, K. Muraki, and S. Tarucha, D. G. Austing'); correct the author separators.
[2.1.2] The symbols Delta_R and Delta_L appear with possible encoding issues in the text; ensure the Greek letters render correctly in the published version.

Circularity Check

0 steps flagged · score 0.0 of 10

No significant circularity: the offset values are model fits presented as estimates, not as predictions derived from themselves.

full rationale

The paper's derivation chain does not reduce to its inputs. The interlayer offsets Δ_R ~ U/2 and Δ_L ~ 3U/2 are obtained by fitting a constant-interaction (CI) model to the positions of kinks and vertical lines in Coulomb diamond data (Sec. 2.1.2). This is an inverse-modeling estimate, not a prediction; the paper labels the results as estimates and does not feed them back into a calculation that purports to predict the same diamonds. The vertical tunnel coupling 2t~0.4meV is taken from earlier published work [14,15] with overlapping authorship, but it is an independent material parameter and not the quantity being derived; the same applies to the charging energy U cited from [17]. The effective isospin Hamiltonian in Sec. 3 follows from a stated second-order perturbation derivation with Jeff~4t²/(U-V), and the discussion of Nagaoka ferromagnetism is explicitly conditional on the fitted offsets being finite and on the site potentials being non-uniform. No equation is equal to another by construction, no fitted parameter is renamed as a prediction, and no load-bearing uniqueness claim rests on the authors' own unverified citations. The main weakness is that the CI fits lack reported parameters and error bars, which is a correctness/underdetermination concern rather than circularity.

Assumptions & free parameters 3 free parameters · 5 assumptions · 0 invented entities

The quantitative results depend on three fitted or implicit parameters: Delta_R, Delta_L, and U, all recovered from CI-model fits. Additional domain assumptions concern the validity of the CI model, the perturbative Hamiltonian, the isospin mapping, and the transferability of earlier tunneling estimates. No new physical entities are introduced; isospin is a relabeling of the layer index.

free parameters (3)

Interlayer offset Delta_R in DQD-R = ~U/2
Estimated by matching the CI-model diamond in Fig. 3(b) to the measured kink and vertical line positions along the A-B line; no independent measurement.
Interlayer offset Delta_L in DQD-L = ~3U/2
Estimated from the CI-model match to three kinks along the C-D line in Fig. 3(d); no uncertainty or independent check.
Intradot charging energy U = not quoted numerically
Used as the energy unit for both offsets; its value is implicitly taken from diamond sizes but never reported.

assumptions (5)

domain assumption The constant-interaction model with fixed capacitances describes the Coulomb diamonds well enough to assign charge states and offsets.
Invoked in Section 2.1.2 and Fig. 3(b,d); offsets are read from CI-model reproductions of kink and vertical line positions.
domain assumption Second-order perturbation theory in the interlayer tunneling t, with t much smaller than U and V, gives J_eff ~ 4t^2/(U-V).
Used in Section 3.1 to write H_eff for the triangular isospin lattice; the inequality is stated but no derivation is shown.
domain assumption The layer index can be mapped to an isospin-1/2 degree of freedom with bonding and antibonding states.
Section 3.1 assumes the low-energy dynamics is governed by the layer index, with spin degrees of freedom neglected.
domain assumption The vertical tunneling 2t ~ 0.4 meV estimated from earlier material work [14,15] applies to the present device.
Section 2.1.1 uses this value to argue that vertical coupling exceeds lateral coupling; it is not remeasured in this device.
domain assumption A triangular array of vertically coupled DQDs is feasible because a triangular array of single vertical dots has been demonstrated [18].
Section 3.1 argues feasibility by analogy to prior fabrication; no triangular DQD device is fabricated in this paper.

how reviews work

0 comments

Cite this review

Pith. "Pith review of Vertically Coupled Double Quantum Dots Connected In Parallel." pith.science (2026). https://pith.science/paper/2RZZWSEB

@misc{pith2026250709598,
  author       = {Pith},
  title        = {Pith review of: Vertically Coupled Double Quantum Dots Connected In Parallel},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/2RZZWSEB}},
  note         = {Machine review of arXiv:2507.09598}
}

read the original abstract

We report charge transport measurements in a ring-shaped quadruple quantum dot system, composed of two vertically coupled double quantum dots connected in parallel. The vertical coupling introduces an isospin degree of freedom tied to the layer index, and the parallel configuration enables independent access to each quantum dot pair. This design allows us to observe Coulomb diamonds and evaluate the interlayer energy offset. By extending this platform to triangular and hexagonal artificial lattices, we explore correlation effects such as isospin frustration. These results highlight the system's potential for studying interaction-driven quantum phases.

Figures

Figures reproduced from arXiv: 2507.09598 by the authors.

**Figure 1.** (a) Schematic diagrams of a QQD device consisting of DQD-L and DQD-R connected in parallel. Only one of the two center gates VGC is shown; the other is located on the back side and not depicted. (b) The current flow in the QQD device. Note that two center gate electrodes are attached to the [PITH_FULL_IMAGE:figures/full_fig_p010_1.png] view at source ↗

**Figure 2.** Current 𝐼𝑑 is mapped as a function of 𝑉𝐺𝐿 and 𝑉𝐺𝑅 under 𝑉𝑠𝑑∼150𝜇eV with (a) 𝑉𝐺𝐶=-0.8V and (b) 𝑉𝐺𝐶=-1.0V [PITH_FULL_IMAGE:figures/full_fig_p010_2.png] view at source ↗

**Figure 3.** (a) Differential conductance 𝑑𝐼𝑑/𝑑𝑉𝑠𝑑 as a function of source-drain voltage 𝑉𝑠𝑑 measured along the A–B line in [PITH_FULL_IMAGE:figures/full_fig_p011_3.png] view at source ↗

Figures from the paper (2 more)

**Figure 4.** Figure 4: Summarized charge configuration (NRU, NRD, NLU, NLD) in [PITH_FULL_IMAGE:figures/full_fig_p011_4.png]

**Figure 5.** Figure 5: (a) Schematic diagram of triangular array of three vertically coupled DQDs. (b) SEM image of an artificial graphene sample composed of vertically QD arranged in a honeycomb geometry without gates [PITH_FULL_IMAGE:figures/full_fig_p012_5.png]

Discussion (0). Continue with ORCID to comment.

Forward citations

Cited by 1 Pith paper

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

The Magic Scroll: Leveraging biased noise to improve magic state cultivation in register-based architectures
quant-ph 2026-08 conditional novelty 6.0 of 10

The Magic Scroll protocol uses biased noise and two-qubit registers to reduce the cost of producing high-fidelity magic T states by about 3x, reaching error rates near 1e-15 when combined with distillation.

Reference graph

Works this paper leans on

23 extracted references · 23 canonical work pages · cited by 1 Pith paper

[1]

Introduction Quantum dots (QDs) are regarded as artificial atoms due to their electronic properties associated with three-dimensional electron confinement [1, 2]. Owing to their discrete energy levels and high tunability, QDs have emerged as a promising platform for quantum information processing [2-5] and the simulation of strongly correlated electron sy...

work page
[2]

The device comprises two pillar-shaped mesas, each incorporating two quantum wells separated by a thin tunneling barrier, thereby forming a vertically coupled DQD

Transport Characteristics of Vertical DQDs coupled in Parallel 2.1 Device Structure Figure 1(a) shows a schematic diagram of a quadruple quantum dot (QQD) device consisting of two vertically coupled double quantum dots (DQDs) connected in parallel. The device comprises two pillar-shaped mesas, each incorporating two quantum wells separated by a thin tunne...

work page
[3]

adatom -like

Multi-Dot Lattices Formed from Vertically Coupled DQDs 3.1 Triangular Array of Vertically Coupled DQDs Building upon the demonstrated hybrid configuration combining vertical and lateral couplings, we now extend our investigation to more complex QD lattices formed by vertically coupled DQDs. Such structures serve as a promising platform for simulating quan...

work page
[4]

The device structure enabled the extraction of the interlayer energy offset, which arises from asymmetries i n confinement or electrostatic potential

Conclusion We have studied charge transport in a four -quantum-dot ring structure composed of two vertically coupled double quantum dots connected in parallel. The device structure enabled the extraction of the interlayer energy offset, which arises from asymmetries i n confinement or electrostatic potential. Coulomb diamond measurements allowed us to ide...

work page 2021
[5]

Tarucha, D

S. Tarucha, D. G. Austing, T. Honda, R. J. van der Hage and L. P. Kouwenhoven, Phys. Rev. Lett. 77, 3613 (1996)

work page 1996
[6]

Burkard, T

G. Burkard, T. D. Ladd, J. M. Nichol, A. Pan and J.R. Petta, Rev. Mod. Phys. 95, 025003 (2023)

work page 2023
[7]

Takeda, J

K. Takeda, J. Kamioka, T. Otsuka, J. Yoneda, T. Nakajima, M.R. Delbecq , S. Amaha, G. Allison, T. Kodera, S. Oda, and S. Tarucha, Sci. Adv. 2, e1600694 (2016)

work page 2016
[8]

Yoneda, J

J. Yoneda, J. S. Rojas-Arias, P. Stano et al. Nat. Phys. 19, 1793 (2023)

work page 2023

Show all 23 references

[9]

X. Yu, B. Wilhelm, D. Holmes et al., Nat. Phys. 21, 362 (2025)

2025
[10]

Amaha, T

S. Amaha, T. Hatano, T. Kubo, S. Teraoka, Y . Tokura, and S. Tarucha, Phys. Rev. B 85, 081301(R) (2012)

2012
[11]

Hensgens, T

T. Hensgens, T. Fujita, L. Janssen et al., Nature 548, 70 (2017)

2017
[12]

J. P. Dehollain, U . Mukhopadhyay, V. P. Michal, Y. Wang, B. Wunsch, C . Reichl, W. 9 Wegscheider, M. S. Rudner, E. Demler, and L. M. K. Vandersypen, Nature 579, 528 (2020)

2020
[13]

Hatano, S

T. Hatano, S. Amaha, T. Kubo, Y . Tokura, Y . Nishi, Y . Hirayama, and S. Tarucha, Phys. Rev. B 77, 241301(R) (2008)

2008
[14]

M. Seo, H. K. Choi, S.-Y . Lee, N. Kim, Y . Chung, H.-S. Sim, V . Umansky, and D. Mahalu, Phys. Rev. Lett. 110, 046803 (2013)

2013
[15]

M. Pi, A. Emperador, M. Barranco, F. Garcias, K. Muraki , and S. Tarucha, D. G. Austing, Phys. Rev. Lett. 87, 66801 (2001)

2001
[16]

Amaha, W

S. Amaha, W. Izumida, T. Hatano, S. Teraoka, S. Tarucha, J. A. Gupta, and D. G. Austing, Phys. Rev. Lett. 110, 016803 (2013)

2013
[17]

Imamura, P

H. Imamura, P. A. Maksym, and H. Aoki, Phys. Rev. B 59, 5817 (1999)

1999
[18]

Rontani, S

M. Rontani, S. Amaha, K. Muraki, F. Manghi, E. Molinari, S. Tarucha, and D. G. Austing, Phys. Rev. B 69, 085327 (2004)

2004
[19]

Amaha, D.G

S. Amaha, D.G. Austing, Y . Tokura, K. Muraki , K. Ono, and S. Tarucha, Solid State Comm. 119, 183 (2001)

2001
[20]

T. Ota, K. Ono, M. Stopa, T. Hatano, S. Tarucha, H. Z. Song, Y . Nakata, T. Miyazawa, T. Ohshima, and N. Yokoyama, Phys. Rev. Lett. 93, 066801 (2004)

2004
[21]

Nakamura, H

S. Nakamura, H. Kiyama, and A. Oiwa, J. Appl. Phys. 132, 224301 (2022)

2022
[22]

Amaha, T

S. Amaha, T. Hatano, T. Kubo, S. Teraoka, Y . Tokura, and S. Tarucha, D. G. Austing, Appl. Phys. Lett. 94, 092103 (2009)

2009
[23]

Polini, F

M. Polini, F. Guinea, M. Lewenstein et al., Nature Nanotech 8, 625 (2013). 10 Figure 1. (a) Schematic diagrams of a QQD device consisting of DQD-L and DQD-R connected in parallel. Only one of the two center gates VGC is shown; the other is located on the back side and not depi...

2013

Pith tools

Reviewed August 6, 2026 · model on record in the stance chip above.

[1] [1]

Introduction Quantum dots (QDs) are regarded as artificial atoms due to their electronic properties associated with three-dimensional electron confinement [1, 2]. Owing to their discrete energy levels and high tunability, QDs have emerged as a promising platform for quantum information processing [2-5] and the simulation of strongly correlated electron sy...

work page

[2] [2]

The device comprises two pillar-shaped mesas, each incorporating two quantum wells separated by a thin tunneling barrier, thereby forming a vertically coupled DQD

Transport Characteristics of Vertical DQDs coupled in Parallel 2.1 Device Structure Figure 1(a) shows a schematic diagram of a quadruple quantum dot (QQD) device consisting of two vertically coupled double quantum dots (DQDs) connected in parallel. The device comprises two pillar-shaped mesas, each incorporating two quantum wells separated by a thin tunne...

work page

[3] [3]

adatom -like

Multi-Dot Lattices Formed from Vertically Coupled DQDs 3.1 Triangular Array of Vertically Coupled DQDs Building upon the demonstrated hybrid configuration combining vertical and lateral couplings, we now extend our investigation to more complex QD lattices formed by vertically coupled DQDs. Such structures serve as a promising platform for simulating quan...

work page

[4] [4]

The device structure enabled the extraction of the interlayer energy offset, which arises from asymmetries i n confinement or electrostatic potential

Conclusion We have studied charge transport in a four -quantum-dot ring structure composed of two vertically coupled double quantum dots connected in parallel. The device structure enabled the extraction of the interlayer energy offset, which arises from asymmetries i n confinement or electrostatic potential. Coulomb diamond measurements allowed us to ide...

work page 2021

[5] [5]

Tarucha, D

S. Tarucha, D. G. Austing, T. Honda, R. J. van der Hage and L. P. Kouwenhoven, Phys. Rev. Lett. 77, 3613 (1996)

work page 1996

[6] [6]

Burkard, T

G. Burkard, T. D. Ladd, J. M. Nichol, A. Pan and J.R. Petta, Rev. Mod. Phys. 95, 025003 (2023)

work page 2023

[7] [7]

Takeda, J

K. Takeda, J. Kamioka, T. Otsuka, J. Yoneda, T. Nakajima, M.R. Delbecq , S. Amaha, G. Allison, T. Kodera, S. Oda, and S. Tarucha, Sci. Adv. 2, e1600694 (2016)

work page 2016

[8] [8]

Yoneda, J

J. Yoneda, J. S. Rojas-Arias, P. Stano et al. Nat. Phys. 19, 1793 (2023)

work page 2023