اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدStrong photon coupling to the quadrupole moment of an electron in solid state
42
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
The implementation of circuit quantum electrodynamics allows coupling distant qubits by microwave photons hosted in on-chip superconducting resonators. Typically, the qubit-photon interaction is realized by coupling the photons to the electric dipole moment of the qubit. A recent proposal suggests storing the quantum information in the electric quadrupole moment of an electron in a triple quantum dot. The qubit is expected to have improved coherence since it is insensitive to dipolar noise produced by distant voltage fluctuators. Here we experimentally realize a quadrupole qubit in a linear array of three quantum dots in a GaAs/AlGaAs heterostructure. A high impedance microwave resonator coupled to the middle dot interacts with the qubit quadrupole moment. We demonstrate strong quadrupole qubit--photon coupling and observe improved coherence properties when operating the qubit in the parameter space where the dipole coupling vanishes.
قيم البحث
اقرأ أيضاً
Circuit quantum electrodynamics allows one to probe, manipulate and couple superconducting quantum bits using cavity photons at an exquisite level. One of its cornerstones is the possibility to achieve the strong coupling which allows one to hybridiz
e coherently light and matter. Its transposition to quantum dot circuits could offer the opportunity to use new degrees of freedom such as individual charge or spin. However, the strong coupling of quantum dot circuits to cavity photons remains to be observed. Here, we demonstrate a hybrid superconductor-quantum dot circuit which realizes the strong coupling of an individual electronic excitation to microwave photons. We observe a vacuum Rabi splitting 2g~10 MHz which exceeds by a factor of 3 the linewidth of the hybridized light-matter states. Our findings open the path to ultra-long distance entanglement of quantum dot based qubits. They could be adapted to many other circuit designs, shedding new light on the roadmap for scalability of quantum dot setups.
Coherent generation of indistinguishable single photons is crucial for many quantum communication and processing protocols. Solid-state realizations of two-level atomic transitions or three-level spin-$Lambda$ systems offer significant advantages ove
r their atomic counterparts for this purpose, albeit decoherence can arise due to environmental couplings. One popular approach to mitigate dephasing is to operate in the weak excitation limit, where excited state population is minimal and coherently scattered photons dominate over incoherent emission. Here we probe the coherence of photons produced using two-level and spin-$Lambda$ solid-state systems. We observe that the coupling of the atomic-like transitions to the vibronic transitions of the crystal lattice is independent of driving strength and detuning. We apply a polaron master equation to capture the non-Markovian dynamics of the ground state vibrational manifolds. These results provide insight into the fundamental limitations for photon coherence from solid-state quantum emitters, with the consequence that deterministic single-shot quantum protocols are impossible and inherently probabilistic approaches must be embraced.
We present a method to implement 3-dimensional polariton confinement with in-situ spectral tuning of the cavity mode. Our tunable microcavity is a hybrid system consisting of a bottom semiconductor distributed Bragg reflector (DBR) with a cavity cont
aining quantum wells (QWs) grown on top and a dielectric concave DBR separated by a micrometer sized gap. Nanopositioners allow independent positioning of the two mirrors and the cavity mode energy can be tuned by controlling the distance between them. When close to resonance we observe a characteristic anticrossing between the cavity modes and the QW exciton demonstrating strong coupling. For the smallest radii of curvature concave mirrors of 5.6 $mu$m and 7.5 $mu$m real-space polariton imaging reveals submicron polariton confinement due to the hemispherical cavity geometry.
Understanding the interaction between cavity photons and electronic nanocircuits is crucial for the development of Mesoscopic Quantum Electrodynamics (QED). One has to combine ingredients from atomic Cavity QED, like orbital degrees of freedom, with
tunneling physics and strong cavity field inhomogeneities, specific to superconducting circuit QED. It is therefore necessary to introduce a formalism which bridges between these two domains. We develop a general method based on a photonic pseudo-potential to describe the electric coupling between electrons in a nanocircuit and cavity photons. In this picture, photons can induce simultaneously orbital energy shifts, tunneling, and local orbital transitions. We study in details the elementary example of a single quantum dot with a single normal metal reservoir, coupled to a cavity. Photon-induced tunneling terms lead to a non-universal relation between the cavity frequency pull and the damping pull. Our formalism can also be applied to multi quantum dot circuits, molecular circuits, quantum point contacts, metallic tunnel junctions, and superconducting nanostructures enclosing Andreev bound states or Majorana bound states, for instance.
First-principles studies of the electron-phonon coupling in graphene predict a high coupling strength for the $sigma$ band with $lambda$ values of up to 0.9. Near the top of the $sigma$ band, $lambda$ is found to be $approx 0.7$. This value is consis
tent with the recently observed kinks in the $sigma$ band dispersion by angle-resolved photoemission. While the photoemission intensity from the $sigma$ band is strongly influenced by matrix elements due to sub-lattice interference, these effects differ significantly for data taken in the first and neighboring Brillouin zones. This can be exploited to disentangle the influence of matrix elements and electron-phonon coupling. A rigorous analysis of the experimentally determined complex self-energy using Kramers-Kronig transformations further supports the assignment of the observed kinks to strong electron-phonon coupling and yields a coupling constant of $0.6(1)$, in excellent agreement with the calculations.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
