Research Topics

The Quantum Nano Engineering Laboratory

Who are we?

Our research is mainly focused on quantum nano-structures. In our work we create a controlled system for room temperature quantum device operation. Our study is exploiting a novel developed "nano-toolbox" that includes nano dots and organic molecules that link the dots to the device.
This methodology is expected to enable the use of quantum mechanics at room temperature, bringing about a new type of devices such as single photon detectors and emitters, light emitting diodes, IR sensors, solar cells, and photo-electrical devices. Moreover, this methodology is aimed at producing a generic technology for constructing nano-systems in which many devices are interconnected, operate in unison, and are coupled to their macroscopic environment without inhibiting their quantum nature. Finally, the suggested methodology has the potential to bring about room temperature non-binary quantum transistors, which can supply a realistic technological chassis for quantum computing.
At present we have fully equipped and functioning lab, divided into four dedicated sections: the Transport and Optical laboratory, Magneto-Optical laboratory, Noise laboratory, and Wet Chemical assembly lab.

Positions available for talented MSc PhD and Post-Doc students. Contact us

 
 
 

Selected Publications

Separation of enantiomers by their enantiospecific interaction with achiral magnetic substrates

May 10, 2018

It is commonly assumed that recognition and discrimination of chirality, both in nature and in artificial systems, depend solely on spatial effects. However, recent studies have suggested that charge redistribution in chiral molecules manifests an enantiospecific preference in electron spin orientation. We therefore reasoned that the induced spin polarization may affect enantiorecognition through exchange interactions. Here, we show experimentally that the interaction of chiral molecules with a perpendicularly magnetized substrate is enantiospecific. Thus, one enantiomer adsorbs preferentially when the magnetic dipole is pointing up, whereas the other adsorbs faster for the opposite alignment of the magnetization. The interaction is not controlled by the magnetic field per se, but rather by the electron spin orientations, and opens prospects for a distinct approach to enantiomeric separations.

Changes in aggregation states of light-harvesting complexes as a mechanism for modulating energy transfer in desert crust cyanobacteria

July 21, 2017

In this paper we propose an energy dissipation mechanism that is completely reliant on changes in the aggregation state of the phycobilisome light-harvesting antenna components. All photosynthetic organisms regulate the efficiency of excitation energy transfer (EET) to fit light energy supply to biochemical demands. Not many do this to the extent required of desert crust cyanobacteria. Following predawn dew deposition, they harvest light energy with maximum efficiency until desiccating in the early morning hours. In the desiccated state, absorbed energy is completely quenched. Time and spectrally resolved fluorescence emission measurements of the desiccated desert crust Leptolyngbya ohadii strain identified (i) reduced EET between phycobilisome components, (ii) shorter fluorescence lifetimes, and (iii) red shift in the emission spectra, compared with the hydrated state. These changes coincide with a loss of the ordered phycobilisome structure, evident from small-angle neutron and X-ray scattering and cryo-transmission electron microscopy data. Based on these observations we propose a model where in the hydrated state the organized rod structure of the phycobilisome supports directional EET to reaction centers with minimal losses due to thermal dissipation. In the desiccated state this structure is lost, giving way to more random aggregates. The resulting EET path will exhibit increased coupling to the environment and enhanced quenching.

Magnetic Memory: Magnetic Nanoplatelet-Based Spin Memory Device Operating at Ambient Temperatures

May 2, 2017

There is an increasing demand for realizing a simple Si based universal memory device working at ambient temperatures. In principle, nonvolatile magnetic memory can operate at low power consumption and high frequencies. However, in order to compete with existing memory technology, size reduction and simplification of the used material systems are essential. In this work, the chiral-induced spin selectivity effect is used along with 30–50 nm ferromagnetic nanoplatelets in order to realize a simple magnetic memory device. The vertical memory is Si compatible, easy to fabricate, and in principle can be scaled down to a single nanoparticle size. Results show clear dual magnetization behavior with threefold enhancement between the one and zero states. The magnetization of the device is accompanied with large avalanche like noise that is ascribed to the redistribution of current densities due to spin accumulation inducing coupling effects between the different nanoplatelets.

Magnetization switching in ferromagnets by adsorbed chiral molecules without current or external magnetic field

February 23, 2017

Ferromagnets are commonly magnetized by either external magnetic fields or spin polarized currents. The manipulation of magnetization by spin-current occurs through the spin-transfer-torque effect, which is applied, for example, in modern magnetoresistive random access memory. However, the current density required for the spin-transfer torque is of the order of 1 × 106 A·cm−2, or about 1 × 1025electrons s−1 cm−2. This relatively high current density significantly affects the devices’ structure and performance. Here we demonstrate magnetization switching of ferromagnetic thin layers that is induced solely by adsorption of chiral molecules. In this case, about 1013electrons per cm2 are sufficient to induce magnetization reversal. The direction of the magnetization depends on the handedness of the adsorbed chiral molecules. Local magnetization switching is achieved by adsorbing a chiral self-assembled molecular monolayer on a gold-coated ferromagnetic layer with perpendicular magnetic anisotropy. These results present a simple low-power magnetization mechanism when operating at ambient conditions.

AFM‐Based Spin‐Exchange Microscopy Using Chiral Molecules

August 18, 2019

Local magnetic imaging at nanoscale resolution is desirable for basic studies of magnetic materials and for numerous applications. However, such local imaging is hard to achieve by means of standard magnetic force microscopy. A simple and robust method for local magnetic imaging based on short‐range spin exchange interactions realized with a chiral‐molecule‐functionalized AFM tip is presented.

Magnetic-related States and Order Parameter Induced in a Conventional Superconductor by Nonmagnetic Chiral Molecules

July 30, 2019

Hybrid ferromagnetic/superconducting systems are well-known for hosting intriguing phenomena such as emergent triplet superconductivity at their interfaces and the appearance of in-gap, spin-polarized Yu–Shiba–Rusinov (YSR) states bound to magnetic impurities on a superconducting surface. In this work we demonstrate that similar phenomena can be induced on a surface of a conventional superconductor by chemisorbing nonmagnetic chiral molecules. Conductance spectra measured on NbSe2 flakes over which chiral α-helix polyalanine molecules were adsorbed exhibit, in some cases, in-gap states nearly symmetrically positioned around zero bias that shift with magnetic field, akin to YSR states, as corroborated by theoretical simulations. Other samples show evidence for a collective phenomenon of hybridized YSR-like states giving rise to unconventional, possibly triplet superconductivity, manifested in the conductance spectra by the appearance of a zero bias conductance that diminishes, but does not split, with magnetic field. The transition between these two scenarios appears to be governed by the density of adsorbed molecules.

Contact Us

Thanks for your interest in our research. Get in touch with us for any questions or comments regarding our work and publications. Positions available for talented MSc PhD and Post-Doc students. We’d love to hear from you.

Applied Physics Department
Faculty of Science
The Hebrew University,
Jerusalem 9190401, Israel

+972-2-6584404

 

Read about our CISS effect research in Physics Today

August 26, 2018

Read about our chirality separation on Ynet (HEBREW)

June 18, 2018

Watch Yossi interview for 'Keshset' networks' morning show about Chiral separation (HEBREW)

May 21, 2018

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+972-2-6585760

+972-2-6584404

Applied Physics Department
Faculty of Science
The Hebrew University,
Jerusalem 9190401, Israel

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