| 1. |
- Haldar, Subhomoy, et al.
(författare)
-
Energetics of Microwaves Probed by Double Quantum Dot Absorption
- 2023
-
Ingår i: Physical Review Letters. - 0031-9007. ; 130:8
-
Tidskriftsartikel (refereegranskat)abstract
- We explore the energetics of microwaves interacting with a double quantum dot photodiode and show wave-particle aspects in photon-assisted tunneling. The experiments show that the single-photon energy sets the relevant absorption energy in a weak-drive limit, which contrasts the strong-drive limit where the wave amplitude determines the relevant-energy scale and opens up microwave-induced bias triangles. The threshold condition between these two regimes is set by the fine-structure constant of the system. The energetics are determined here with the detuning conditions of the double dot system and stopping-potential measurements that constitute a microwave version of the photoelectric effect.
|
|
| 2. |
- Haldar, Subhomoy, et al.
(författare)
-
Microwave power harvesting using resonator-coupled double quantum dot photodiode
- 2024
-
Ingår i: Physical Review B. - 2469-9950. ; 109:8
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a microwave power-to-electrical energy conversion in a resonator-coupled double quantum dot. The system, operated as a photodiode, converts individual microwave photons to electrons tunneling through the double dot, resulting in an electrical current flowing against the applied voltage bias at input powers down to 1 fW. The device attains a maximum power harvesting efficiency of 2%, with the photon-to-electron conversion efficiency reaching 12% in the single-photon absorption regime. We find that the power conversion depends on thermal effects showing that thermodynamics plays a crucial role in the single-photon energy conversion.
|
|
| 3. |
- Havir, Harald, et al.
(författare)
-
Quantum dot source-drain transport response at microwave frequencies
- 2023
-
Ingår i: Physical Review B. - 2469-9950. ; 108:20
-
Tidskriftsartikel (refereegranskat)abstract
- Quantum dots are frequently used as charge-sensitive devices in low-temperature experiments to probe electric charge in mesoscopic conductors where the current running through the quantum dot is modulated by the nearby charge environment. Recent experiments have operated these detectors using reflectometry measurements up to gigahertz frequencies rather than probing the low-frequency current through the dot. In this work, we use an on-chip coplanar waveguide resonator to measure the source-drain transport response of two quantum dots at a frequency of 6 GHz, further increasing the bandwidth limit for charge detection. Similar to that in the low-frequency domain, the response is here predominantly dissipative. For large tunnel coupling, the response is still governed by the low-frequency conductance, in line with Landauer-Büttiker theory. For smaller couplings, our devices showcase two regimes where the high-frequency response deviates from the low-frequency limit and Landauer-Büttiker theory: When the photon energy exceeds the quantum dot resonance linewidth, degeneracy-dependent plateaus emerge. These are reproduced by sequential tunneling calculations. In the other case with large asymmetry in the tunnel couplings, the high-frequency response is two orders of magnitude larger than the low-frequency conductance G, favoring the high-frequency readout.
|
|
