Shahal Ilani
Weizmann Institute
Tuesday 19th January 16:40 – 17:20 CET
ZOOM LINK TO JOIN IN: http://s.ic.fo/FNS2021_Jan19
An atomic-like qubit in carbon nanotubes
By Shahal Ilani
Department of Condensed Matter Physics, Weizmann Institute of Science, Israel
ABSTRACT:
Quantum sensing techniques have been successful in pushing the sensitivity limits in numerous fields, and hold great promise for scanning probes that study nano-scale devices and novel materials. However, forming a nano-scale qubit that is simple and robust enough to be placed on a scanning tip, and sensitive enough to detect various physical observables, is still a great challenge. Here we demonstrate a conceptually new qubit implementation in a carbon nanotube that achieves these requirements. In contrast to the prevailing semiconducting qubits that use electronic states in double quantum dots, our qubit utilizes the natural electronic wavefunctions in a single quantum dot. Using an ultra-clean nanotube we construct a qubit from two wavefunctions with significantly different magnetic moments and spatial charge distributions, making it sensitive to both magnetic and electric fields. We use an array of gates to directly image these wavefunctions and demonstrate their localized moments. Owing to their different spatial structure, these wavefunctions also show radically different transport properties, giving us a simple transport-based qubit readout mechanism. Due to its narrow coherence-limited transition, the qubit demonstrates significantly better electric field detection sensitivity than a single electron transistor. Moreover, with the same qubit we demonstrate simultaneous probing of magnetic fields with DC sensitivity comparable to that of NV centers. Our technique has minimal requirements for device complexity, which can be implemented using a number of straightforward fabrication methods. These features make this atomic-like qubit a powerful new tool that enables a variety of new nanoscale imaging experiments.
BIO:
Shahal Ilani is an associate professor of experimental condensed matter physics in the Weizmann Institute of Science. He received his PhD from the Weizmann institute, working with Amir Yacoby on scanning single-electron-transistor experiments of two-dimensional electron systems.
His postdoc in Cornell University, with Paul McEuen focused on studies of fundamental properties of carbon nanotubes.
Since 2008 he leads the quantum nano-electronics group in Weizmann. His group developed a nano-assembly technique for making complex quantum devices out of electronically-pristine carbon nanotubes, and use these devices to study the physics of interacting electrons and nano-mechanics in one dimension. They also use nanotubes as ultrasensitive scanning nanoscale detectors of electric potential to visualize fundamental phenomena in various quantum systems. Recent examples include the visualization of the flow of hydrodynamic electrons in graphene, the imaging of the Wigner crystal of electrons, the demonstration of electron attraction via Coulomb repulsion, and the discoveries of new phases in magic angle twisted bilayer graphene.