Christian Spånslätt Rugarn

Delta-T and heat current noise

Electronic shot noise arises from the fact that electrical current is carried by individual, charged particles. In the the last decades, this noise has developed into a ubiquitous tool for characterizing nanoscale systems. For example, it has been used to reveal the charge of fractionalized quasiparticles in the fractional quantum Hall effect, and Cooper-pairs as well as Bogoliubov quasiparticles in superconductors.

More recently, the shot noise in response to a temperature gradient and in the absence of a voltage bias – called delta-T noise – has emerged as novel type of shot noise. In my research, I investigate how delta-T noise can provide additional insights beyond those of the traditional shot noise. I also investigate how fluctuations in the currents, heat-current noise, probe the properties of nanoscale devices.

Thermodynamic and energetic constraints on transition probabilities of small-scale quantum systems

L. Tesser, M. Acciai, C. Spånslätt, I. Safi, and J. Splettstoesser; Phys. Rev. Research 7, 023084 (2025) ; arXiv: 2409.00981

Role of scaling dimensions in generalized noises in fractional quantum Hall tunneling due to a temperature bias;

M.Acciai, G.Zhang, and C. Spånslätt: SciPost Phys. 18, 058 (2025); arXiv: 2408.04525

Impact of potential and temperature fluctuations on charge and heat transport in quantum Hall edges in the heat Coulomb blockade regime;

C. Spånslätt, F. Stäbler, E.V. Sukhorukov, and J. Splettstoesser: Phys. Rev. B 110, 075431 (2024) arXiv: 2406.08910

Charge, spin, and heat shot noises in the absence of average currents: Conditions on bounds at zero and finite frequencies;

L. Tesser, M. Acciai, C. Spånslätt, J. Monsel, and J. Splettstoesser; Phys. Rev. B 107, 075409 (2023); arXiv: 2210.06051

Delta-T noise for weak tunneling in one-dimensional systems: Interactions versus quantum statistics

G. Zhang, I.V. Gornyi, and C. Spånslätt, Physical Review B 105 195423 (2022); arXiv: 2201.13174 (selected as Editor's suggestion)

quantum Hall edge transport

The fractional quantum Hall effect refers to the fractional quantization of the Hall resistance of a strongly interacting two-dimensional electron gas. Such a gas can be created, e.g., in semiconducting heterostructures or in graphene. In a strong magnetic field and at low temperatures, the electron gas enters a globally correlated state with truly remarkable properties. Related to the fractional Hall resistance, the basic excitations of this correlated state have electrical charges which are only fractions of the fundamental electron charge.

A viable route to probe the properties of the fractional quantum Hall states is the edge of the sample. While the bulk system is insulating, the edge is conducting and provides an ideal platform for studying strongly correlated one-dimensional quantum systems.

In particular, the electrical and thermal transport properties of fractional quantum Hall edges, can be used to investigate fundamental bounds on charge and heat transfer. In my research, I develop models of edge transport in close connection to state-of-the art-experiments.

Exchange-phase erasure in anyonic Hong-Ou-Mandel interferometry;

S. Varada, C. Spånslätt, and M. Acciai; Phys. Rev. B 111, L201407 (2025); arXiv: 2503.01678

Fingerprints of anti-Pfaffian topological order in quantum point contact transport;

J. Park, C. Spånslätt, and A.D. Mirlin: Phys. Rev. Lett. 132, 256601 (2024) arXiv: 2402.02157

Electrical noise spectroscopy of magnons in a quantum Hall ferromagnet;

R. Kumar, S.K. Srivastav, U. Roy, J. Park, C. Spånslätt, K. Watanabe, T. Taniguchi, Y. Gefen, A.D. Mirlin, and A. Das; Nat Commun 15, 4998 (2024); arXiv: 2310.08703

Transport signatures of fractional quantum Hall binding transitions;

C. Spånslätt, A. Stern, and A.D. Mirlin; Phys. Rev. B 107, 245405 (2023); arXiv: 2203.05781

Thermal conductance and noise of Majorana modes along interfaced ν = 5/2 fractional quantum Hall states;

M. Hein and C. Spånslätt; Phys. Rev. B 107, 245301 (2023); arXiv: 2211.08000

Determination of topological edge quantum numbers of fractional quantum Hall phases by thermal conductance measurements;

S.K. Srivastav, R. Kumar, C. Spånslätt, K. Watanabe, T. Taniguchi, A.D. Mirlin, Y. Gefen, and A. Das; Nat Commun 13, 5185 (2022); arXiv: 2202.00490

Absent thermal equilibration on fractional quantum Hall edges over macroscopic scale

R. A. Melcer, B. Dutta, C. Spånslätt, J. Park, A.D. Mirlin, V. Umansky, Nat Commun 13, 376 (2022); arXiv: 2106.12486

Observation of ballistic upstream modes at fractional quantum Hall edges of graphene

R. Kumar, S.K. Srivastav, C. Spånslätt, K. Watanabe, T. Taniguchi, Y. Gefen, A.D. Mirlin, and A. Das, Nat Commun 13, 213 (2022); arXiv: 2107.12616

Contacts, equilibration, and interactions in fractional quantum Hall edge transport

C. Spånslätt, Y. Gefen, I.V. Gornyi, and D.G. Polyakov, Phys. Rev. B 104, 115416 (2021); arXiv: 2105.04013

Vanishing thermal equilibration for hole-conjugate fractional quantum Hall states in graphene

S.K. Srivastav, R. Kumar, C. Spånslätt, K. Watanabe, T. Taniguchi, A.D. Mirlin, Y. Gefen, and A. Das, Phys. Rev. Lett. 126, 216803 (2021); arXiv:2010.01090 (selected as Editor's suggestion)

Noise on the non-Abelian ν=5/2 fractional quantum Hall edge

J. Park, C. Spånslätt, Y. Gefen, and A.D. Mirlin, Phys.Rev. Lett. 125, 157702 (2020); arXiv:2006.06018

Conductance plateaus and shot noise in fractional quantum Hall point contacts

C. Spånslätt, J. Park, Y. Gefen, A.D. Mirlin, Phys.Rev.B 101, 075308 (2020); arXiv:1911.11821

Topological classification of shot noise on fractional quantum Hall edges

C. Spånslätt, J. Park, Y. Gefen, A.D. Mirlin, Phys.Rev.Lett. 123, 137701 (2019) ; arXiv:1906.05623

(selected as Editor's suggestion)

Majorana zero modes

Majorana zero modes (MZMs) are zero energy bound states predicted to exist in certain superconducting systems. These states signal that the superconductor is in a special kind of topolgical state, fundamentally distinct from a conventional superconductor.

Apart from being interesting in their own right, MZMs have one particularly attractive property. They realize what is called non-Abelian statistics, meaning that spatially interchanging a set of MZMs can generate new quantum states. This statistical property is hypothesized to form the corner stone of a future topological quantum computer, and has spurred a huge amount of both theoretical and experimental research in the last decades. In my research, I develop models on how to detect MZMs in setups based on superconducting wires.

Distinguishing between Topological and Quasi Majorana Zero Modes with a Dissipative Resonant Level

G. Zhang and C. Spånslätt, Phys.Rev. B 102, 045111 (2020); arXiv:2002.04408

Geometric Josephson effects in chiral topological nanowires

C. Spånslätt, Phys.Rev. B 98, 054508 (2018); arXiv:1804.06901

Extended Majorana zero modes in a topological superconducting-normal T-junction

C. Spånslätt and E. Ardonne, J. Phys. C 29, 105602 (2017); arXiv:1606.06920

Topological aspects of Josephson π-junctions in superconducting wires

C. Spånslätt, E. Ardonne, J.C. Budich, T.H. Hansson,

J. Phys. C, 27, 405701 (2015); arXiv:1501.03413

Effective field theories for topological states of matter

Inspired by research from the 1980's, it was realized in the recent decades that there exsists a huge class of condensed matter systems that cannot be described by the Landau symmetry breaking principle: that phases of matter can be classified according to which symmetries they break. This class of systems is called topological states of matter, since their features are encoded by topological, i.e. non-local, properties in the underlying mathematical framework.

One important question regarding the topological states is how they can be described by quantum field theories that captures the most relevant features related to topology. Such theories are usually called effective field theories or topological field theories. Notable examples are the Chern-Simons theories of the integer- and fractional quantum Hall effects, or the BF-theories of superconductors. These theories capture important properties such as the charges and statistics of low energy excitations and ground state degeneracies. Equally important, they describe the response of the system due to exernal perturbations such as electromagnetic fields. In my research, I have investigated how the response due to certain electromagnetic perturbations can be exploited to mathematically characterize topological states of matter.

Non-local Order Parameters for States with Topological Electromagnetic Response

T. K. Kvorning, C. Spånslätt, A. P. O. Chan, and S. Ryu, Phys.Rev. B 101, 205101 (2020); arXiv:1912.06159

Broad interests

Strongly correlated electrons in low-dimensional systems
Quantum Hall effects and abelian and non-Abelian anyons
One-dimensional quantum systems: conventional-, helical- and chiral Luttinger liquids
Non-equilibrium quantum transport
Quantum field theory
General aspects of topological states of matter, topological insulators and superconductors

Page updated

Google Sites

Report abuse