Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userFunctional advantages offered by many-body coherences in biochemical systems
88
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Quantum coherence phenomena driven by electronic-vibrational (vibronic) interactions, are being reported in many pulse (e.g. laser) driven chemical and biophysical systems. But what systems-level advantage(s) do such many-body coherences offer to future technologies? We address this question for pulsed systems of general size N, akin to the LHCII aggregates found in green plants. We show that external pulses generate vibronic states containing particular multipartite entanglements, and that such collective vibronic states increase the excitonic transfer efficiency. The strength of these many-body coherences and their robustness to decoherence, increase with aggregate size N and do not require strong electronic-vibrational coupling. The implications for energy and information transport are discussed.
rate research
Read More
We propose a dissipative method for the preparation of many-body steady entangled states in spin and fermionic chains. The scheme is accomplished by means of an engineered set of Lindbladians acting over the eigenmodes of the system, whose spectrum is assumed to be resolvable. We apply this idea to prepare a particular entangled state of a spin chain described by the XY model, emphasizing its generality and experimental feasibility. Our results show that our proposal is capable of achieving high fidelities and purities for a given target state even when dephasing and thermal dissipative processes are taken into account. Moreover, the method exhibits a remarkable robustness against fluctuations in the model parameters.
We propose a technique for polarizing and cooling finite many-body systems using feedback control. The technique requires the system to have one collective degree of freedom conserved by the internal dynamics. The fluctuations of other degrees of freedom are then converted into the growth of the conserved one. The proposal is validated using numerical simulations of classical and quantum spin systems in a setting representative of Nuclear Magnetic Resonance experiments. In particular, we were able to achieve 90 percent polarization for a lattice of 1000 classical spins starting from an unpolarized infinite temperature state.
We propose a method to obtain optimal protocols for adiabatic ground-state preparation near the adiabatic limit, extending earlier ideas from [D. A. Sivak and G. E. Crooks, Phys. Rev. Lett. 108, 190602 (2012)] to quantum non-dissipative systems. The space of controllable parameters of isolated quantum many-body systems is endowed with a Riemannian quantum metric structure, which can be exploited when such systems are driven adiabatically. Here, we use this metric structure to construct optimal protocols in order to accomplish the task of adiabatic ground-state preparation in a fixed amount of time. Such optimal protocols are shown to be geodesics on the parameter manifold, maximizing the local fidelity. Physically, such protocols minimize the average energy fluctuations along the path. Our findings are illustrated on the Landau-Zener model and the anisotropic XY spin chain. In both cases we show that geodesic protocols drastically improve the final fidelity. Moreover, this happens even if one crosses a critical point, where the adiabatic perturbation theory fails.
We present experimental coherent two-dimensional Fourier transform spectra of the exciton resonances in semiconductor quantum wells for a pulse sequence that isolates two-quantum coherences. By measuring the real part of the spectra, we can determine that the spectra are dominated by two quantum coherences due to many-body interactions, not bound biexcitons. Simulations performed using dynamics controlled truncation agree well with the experiments.
Recently, nanomaterials are arousing increasing interest and a wide variety of opto-electronic devices have been developed, such as light-emitting diodes, solar cells, and photodetectors. However, the study of the light emission properties of quantum dots under pressure is still limited. By using a joint theoretical and experimental approach, we developed a polymer waveguide doped with CdSe quantum dots for pressure sensing. Absorption and re-emission effects of the quantum dots are affected by the pressure applied on the waveguide. Specifically, since both amplitude and wavelength are modulated, not only the pressure can be detected, but also its location along the waveguide. The calibration results demonstrate the feasibility of the proposed force sensor design. Theoretical model and simulations further validate the presented sensing principle. The proposed prototype benefits from the main advantages of optical sensors, such as their predisposition to miniaturization, small cable sizes and weights, immunity to electromagnetic interference, and safe operation in hazard environments. In addition, bio-compatibility, non-toxicity and flexibility make the presented sensor potentially appealing to various application fields such as nanobiotechnology and robotic sensing.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
