Work package 3
Quantum references beyond the SI
Task 1
Led by CEA
Electronic Mach-Zehnder interferometer
CEA will integrate gate-controlled interference devices, made by UPSaclay, in the QAH regime to
define a tunable electronic MZI. Interference of co-propagating QAH edge channels will give access to
coherence properties of the system. CEA will study the interference visibility for interferometers of
different length and extract the coherence length of the MATBG. This will be the first realization of
an electronic MZI at zero magnetic field, which will be further used as a quantum sensor to probe
the QAHE robustness at finite energy and elevated temperature. The same kind of devices will be
investigated by UCL using SGM where the scanning tip will be used to act as a punctual defect and
reveal the robustness of the MZI as a coherence sensor.
Task 2
Led by CEA
Single-electron detection and tomography
The CEA will use one of the two electronic beam splitters of the MZI, made by UPSaclay, to perform
electron collision experiments or Hong-Ou-Mandel experiment. For the electron tomography, a single
electron excitation (Leviton) is emitted. On the other side, a small sine excitation is sent [19]. By
measuring the current fluctuations at the output of the electron beam splitter, CEA will compute
the electron Wigner function and perform the first tomography of a single electron in MATBG. The
quantum tomography is one of the reference measurement for quantum applications.
Task 3
Led by LMU
Broad band, energy resolving single-photon detectors
LMU will utilize the record low electronic heat capacity Ce ∼ 100 kb and the sharp SC transition of
MATBG (with a Tc ∼ 1K) to create MATBG based SC nano-calorimeter devices that would allow broad
band thermal detection of single photons for visible, the mid-infrared (mid-IR), all the way to the THz
wavelengths, with an energy resolution of 1 THz.