Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userThe visibility study of S-T$_+$ Landau-Zener-Stu007fuckelberg oscillations without applied initialization
74
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Probabilities deduced from quantum information studies are usually based on averaging many identical experiments separated by an initialization step. Such initialization steps become experimentally more challenging to implement as the complexity of quantum circuits increases. To better understand the consequences of imperfect initialization on the deduced probabilities, we study the effect of not initializing the system between measurements. For this we utilize Landau-Zener-Stuckelberg oscillations in a double quantum dot circuit. Experimental results are successfully compared to theoretical simulations.
rate research
Read More
A simple mechanical analog describing Landau-Zener tunneling effect is proposed using two weakly coupled chains of nonlinear oscillators with gradually decreasing (first chain) and increasing (second chain) masses. The model allows to investigate nonlinear generalization of Landau-Zener tunneling effect considering soliton propagation and tunneling between the chains. It is shown that soliton tunneling characteristics become drastically dependent on its amplitude in nonlinear regime. The validity of the developed tunneling theory is justified via comparison with direct numerical simulations on oscillator ladder system.
By driving a 3D transmon with microwave fields, we generate an effective avoided energy-level crossing. Then we chirp microwave frequency, which is equivalent to driving the system through the avoided energy-level crossing by sweeping the avoided crossing. A double-passage chirp produces Landau-Zener-Stuckelberg-Majorana interference that agree well with the numerical results. Our method is fully applicable to other quantum systems that contain no intrinsic avoided level crossing, providing an alternative approach for quantum control and quantum simulation.
We study Landau-Zener macroscopic quantum transitions in ferromagnetic metal nanoparticles containing on the order of 100 atoms. The model that we consider is described by an effective giant-spin Hamiltonian, with a coupling to a random transverse magnetic field mimicking the effect of quasiparticle excitations and structural disorder on the gap structure of the spin collective modes. We find different types of time evolutions depending on the interplay between the disorder in the transverse field and the initial conditions of the system. In the absence of disorder, if the system starts from a low-energy state, there is one main coherent quantum tunneling event where the initial-state amplitude is completely depleted in favor of a few discrete states, with nearby spin quantum numbers; when starting from the highest excited state, we observe complete inversion of the magnetization through a peculiar ``backward cascade evolution. In the random case, the disorder-averaged transition probability for a low-energy initial state becomes a smooth distribution, which is nevertheless still sharply peaked around one of the transitions present in the disorder-free case. On the other hand, the coherent backward cascade phenomenon turns into a damped cascade with frustrated magnetic inversion.
We perform Landau-Zener-Stuckelberg-Majorana (LZSM) spectroscopy on a system with strong spin-orbit interaction (SOI), realized as a single hole confined in a gated double quantum dot. In analogy to the electron systems, at magnetic field B=0 and high modulation frequencies we observe the photon-assisted tunneling (PAT) between dots, which smoothly evolves into the typical LZSM funnel-shaped interference pattern as the frequency is decreased. In contrast to electrons, the SOI enables an additional, efficient spin-flipping interdot tunneling channel, introducing a distinct interference pattern at finite B. Magneto-transport spectra at low-frequency LZSM driving show the two channels to be equally coherent. High-frequency LZSM driving reveals complex photon-assisted tunneling pathways, both spin-conserving and spin-flipping, which form closed loops at critical magnetic fields. In one such loop an arbitrary hole spin state is inverted, opening the way toward its all-electrical manipulation.
Reading out Majorana bound states (MBSs) is essential both to verify their non-Abelian property and to realize topological quantum computation. Here, we construct a protocol to measure the parity of two MBSs in a Majorana island coupled to double quantum dot (DQD). The parity information is mapped to the charge state of the DQD through Landau-Zener transition. The operation needed is sweeping the bias of the DQD, which is followed by charge sensing. In the case without fine-tuning, a single run of sweep-and-detection implement a weak measurement of the parity. We find that in general a sequence of about ten runs would completely project a superposition state to either parity, and the charge detection in each run records how the state of MBSs collapses step by step. Remarkably, this readout protocol is of non-demolition and robust to low frequency charge fluctuation.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
