Heat is usually treated as an unavoidable by-product of electronic operation. In my research, I take the opposite perspective: heat currents can be engineered, guided, modulated, and measured with the same level of control we typically reserve for charge currents—especially in superconducting nanostructures, where quantum coherence and phase sensitivity can strongly shape energy transport.
This area sits at the intersection of mesoscopic superconductivity, nonequilibrium transport, and device-oriented calorimetry, and it is often referred to as coherent caloritronics: using superconducting phase coherence to control heat flow in solid-state nanocircuits.
In superconducting weak links (tunnel junctions, proximized links, interferometers), the energy flow is not only driven by a temperature bias; it can also depend on magnetic flux and on the superconducting phase difference. This makes it possible to create thermal analogues of familiar electronic building blocks:
thermal modulators (flux-controlled heat valves),
thermal memories (bistable heat-flow states encoding information),
thermal routers (directional redistribution of heat among terminals),
heat oscillators (time-dependent heat currents controlled by phase dynamics),
threshold calorimeters (ultra-sensitive detectors triggered by energy absorption events).
A key message I aim to convey—particularly to students—is that in these systems coherence is not a “small correction”: phase-sensitive terms can dominate the response, enable interference-like effects for heat currents, and unlock new device concepts that are hard to realize in normal-metal platforms.
A distinctive line of my work concerns long Josephson junctions, where the electrodynamics is described by sine-Gordon physics and the system supports solitons (fluxons). In these devices, the local phase profile is not uniform and can host traveling excitations—so the thermal transport problem becomes genuinely spatiotemporal.
In practice, this enables concepts such as:
solitonic thermal transport, where heat flow is modulated or conveyed by fluxons,
phase-coherent heat oscillators, where the interplay of bias, dissipation, and nonlinear dynamics produces controllable time-dependent thermal signals,
flux-flow and dynamical regimes with characteristic thermal fingerprints that can be exploited as diagnostic tools or operating points for devices.
This direction naturally bridges condensed-matter theory, nonlinear dynamics, and the “engineering mindset” needed to translate mechanisms into working device proposals.
Superconductors are often associated with suppressed thermoelectric effects, yet in hybrid structures and in unconventional superconductors, thermoelectricity can re-emerge in revealing ways. I work on thermoelectric response in superconducting tunnel junctions and interferometric devices, with two complementary goals:
Functional devices
Designing architectures where thermoelectric signals are enhanced and controllable—e.g., devices that behave as thermoelectric interferometers or that produce bipolar response under controlled conditions.
Spectroscopic diagnostics
Using thermoelectric measurements to infer microscopic information—most notably signatures of order-parameter symmetries in superconductors. In this sense, thermoelectricity is not merely an output: it becomes a probe of pairing symmetry and quasiparticle structure.
Another important component of this theme is calorimetric detection in superconducting circuits. A particularly powerful strategy is threshold calorimetry: engineer a device so that absorbing a small amount of energy produces a sharp, detectable switching event. This links naturally to Josephson physics, where metastable states and switching thresholds are intrinsic.
In such devices, modeling must treat:
nonequilibrium quasiparticle/thermal dynamics,
phase-dependent heat currents,
and realistic noise sources that set false-trigger rates and energy resolution.
This is a good example of how my work often ties together mesoscopic transport, nonlinear dynamics, and stochastic modeling into a unified device-level prediction.
Theoretical progress in coherent caloritronics typically requires combining multiple layers of description:
Microscopic/mesoscopic transport (tunneling theory, quasiparticles, proximized spectra),
Phase-coherent superconducting circuit modeling (interferometers, flux control),
Nonlinear dynamics (especially in extended junctions and dynamical regimes),
Nonequilibrium thermal modeling (temperature profiles, thermalization, time constants),
Connection to measurable observables (thermal modulation curves, response functions, threshold switching metrics).
Projects in this area can be tailored to be highly concrete and “device-facing,” which makes them great for MSc/PhD theses and for theory–experiment collaborations:
Design and optimization of phase-tunable thermal elements
Identify architectures maximizing thermal modulation depth versus realistic losses and thermalization constraints.
Thermal signatures of nonlinear Josephson dynamics
Predict experimentally robust thermal fingerprints of fluxons/breathers/flux-flow regimes and propose measurement protocols.
Thermoelectric interferometry as a symmetry probe
Develop modeling pipelines linking measured thermoelectric response to candidate order-parameter symmetries.
Threshold calorimetry: performance and noise
Quantify false-trigger rates, energy resolution, and optimal operating points under realistic noise and thermal backgrounds.
If you have (or plan) an experimental platform—S-I-S junctions, SQUIPT-like interferometers, long junctions, multilayer stacks—I can adapt the modeling to your geometry and constraints and help define measurements that best discriminate competing mechanisms.
C. Guarcello, F. Giazotto, P. Solinas, Coherent diffraction of thermal currents in long Josephson tunnel junctions, Phys. Rev. B 94, 054522 (2016).
C. Guarcello, P. Solinas, M. Di Ventra, F. Giazotto, Hysteretic superconducting heat-flux quantum modulator, Phys. Rev. Applied 7, 044021 (2017).
C. Guarcello, P. Solinas, A. Braggio, M. Di Ventra, F. Giazotto, Josephson Thermal Memory, Phys. Rev. Applied 9, 014021 (2018).
C. Guarcello, P. Solinas, A. Braggio, F. Giazotto, Phase-coherent solitonic Josephson heat oscillator, Sci. Rep. 8, 12287 (2018).
C. Guarcello, P. Solinas, A. Braggio, F. Giazotto, Solitonic thermal transport in a current biased long Josephson junction, Phys. Rev. B 98, 104501 (2018).
C. Guarcello, A. Braggio, P. Solinas, G. P. Pepe, F. Giazotto, Josephson-threshold calorimeter, Phys. Rev. Applied 11, 054074 (2019).
C. Guarcello, A. Braggio, P. Solinas, F. Giazotto, Nonlinear Critical-Current Thermal Response of an Asymmetric Josephson Tunnel Junction, Phys. Rev. Applied 11, 024002 (2019).
C. Guarcello, P. Solinas, F. Giazotto, A. Braggio, Thermal flux-flow regime in long Josephson tunnel junctions, J. Stat. Mech. (2019) 084006.
C. Guarcello, R. Citro, F. Giazotto, A. Braggio, Temperature-biased double-loop Josephson flux transducer, Phys. Rev. Applied 18, 014037 (2022).
C. Guarcello, R. Citro, F. Giazotto, A. Braggio, Bipolar thermoelectrical SQUIPT (BTSQUIPT), Appl. Phys. Lett. 123, 152601 (2023).
C. Guarcello, A. Braggio, F. Giazotto, R. Citro, Thermoelectric signatures of order-parameter symmetries in iron-based superconducting tunnel junctions, Phys. Rev. B 108, L100511 (2023).