The AMOS weekly seminar takes place on Tuesdays 13:30-14:20 in the Weismann Auditorium.

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For more information, please contact the organizers:

Inbar Aharon: inbar.aharon@weizmann.ac.il

Omri Davidson: omri.davidson@weizmann.ac.il

## Upcoming seminars

### 07.12.2021 | Seminar

**All-optical noise spectroscopy of solid-state spin qubits**

The development of spin qubits with long coherence times for quantum information processing requires sources of spin noise to be identified and minimized. Although microwave-based spin control is typically used to extract the noise spectrum, this becomes infeasible when high frequency noise components are stronger than the available microwave power. Here, we introduce an all-optical approach for noise spectroscopy of spin qubits. Our approach is based on Raman spin rotation for the application of coherent control pulse sequences inspired by nuclear magnetic resonance spectroscopy. By analyzing the resulting spin dynamics, we extract the noise spectrum of a single electron confined in a quantum dot, which represents its hyperfine interaction with an ensemble of nuclear spins broadened by strain. Our Raman-based analysis provides insights for extending the coherence times and predicts the dynamics of optically-active spin systems. Such understanding is crucial for the development of qubits with long coherence times toward novel applications in quantum information processing and quantum sensing.

### 14.12.2021 | Defence đźŽ“

TBD

### 16.12.2021 | Seminar

TBD

### 20.12.2021 | Seminar

**Note the special date and time!**

**Quantum inference: unraveling â€śwhich pathway?â€ť information**

Quantum systems are remarkably sensitive to changes in their environment. This renders them extraordinary probes for sensing applications. In contrast to classical probes, they undergo transitions upon coupling that encode trajectory dependent quantum information in their statistics. Decoding this information requires a new set of inference methodologies, such as the one we introduce here.

Entangled photon pairs have inspired a myriad of quantum-enhanced metrology platforms, which outperform their classical counterparts. However, the role of photon exchange-phase and degree of distinguishability have not yet been utilized in quantum-enhanced applications. We show that when a two-photon wave-function is coupled to matter, it is encoded with â€śwhich pathway?â€ť information even at a low degree of entanglement. An interferometric exchange-phase-cycling protocol is developed, revealing phase-sensitive information for each interaction history individually. Moreover, we find that quantum-light multimode interferometry introduces a new set of time variables that enable time-resolved signals, unbound by uncertainty to the inverse bandwidth of the wave-packet. We illustrate our findings on an exciton model-system and discuss future applications.

### 04.01.2022 | Seminar

**Nanophotonic structure-mediated free-electron acceleration and manipulation in the classical and quantum regimes**

Dielectric laser accelerators (DLA) are, fundamentally, the interaction of photons with free electrons, where energy and momentum conservation are satisfied by mediation of a nanostructure. In this scheme, the photonic nanostructure induces near-fields, which transfer energy from the photon to the electron via the inverse-Smith-Purcell effect [1,2]. Research in this direction is a wonderful opportunity to engage in multi-disciplinary science, because it directly involves accelerator physics, quantum physics, electron microscopy, ultrafast lasers, near-field optics, and nanofabrication. There is great potential for DLA to provide ground-breaking applications, as it is the only technology promising to miniaturize particle accelerators down to the chip-scale. This is because dielectric materials allow using an order of magnitude larger electric fields, relative to metallic radiofrequency (RF) acceleration cavities. Further, modern ultrafast lasers are perfectly poised to induce these high fields, and have additional advantages over RF technology, including high repetition rates, femtosecond temporal period, and inherent phase-locking to the electron pulse, when the latter is generated by the same laser. This fundamental interaction can also be used to study and demonstrate quantum photon-electron interaction. Photon-induced electron-microscopy (PINEM), first observed in 2009 and intended for applications in microscopy [3], has since evolved to be a fruitful source of photon-electron quantum phenomena. In particular, the free electronâ€™s energy spectrum can be measured and shown to have discrete energy peaks, spaced with the interacting photon energy, and correlated to the number of photon exchanges that took place during the interaction. In this seminar, I will introduce you to the field of DLA. I will discuss the general prospects of DLA beyond its initial goal - electron acceleration - and towards the rich physics of photon-electron interaction with nanostructures. Our recently-published demonstration of free-electron transport in a nanophotonic structure will be presented [4], along with results from our recently-submitted work on measurements of photon-energy-resolved energy peaks, which were measured in a scanning electron microscope for the first time [5].

1. J. Breuer and P. Hommelhoff, "Laser-based acceleration of nonrelativistic electrons at a dielectric structure," Phys. Rev. Lett. 111, (2013).

2. E. A. Peralta, K. Soong, R. J. England, E. R. Colby, Z. Wu, B. Montazeri, C. McGuinness, J. McNeur, K. J. Leedle, D. Walz, E. B. Sozer, B. Cowan, B. Schwartz, G. Travish, and R. L. Byer, "Demonstration of electron acceleration in a laser-driven dielectric microstructure," Nature 503, 91â€“94 (2013).

3. B. Barwick, D. J. Flannigan, and A. H. Zewail, "Photon-induced near-field electron microscopy," Nature 462, 902 (2009).

4. R. Shiloh, J. Illmer, T. Chlouba, P. Yousefi, N. SchĂ¶nenberger, U. Niedermayer, A. Mittelbach, and P. Hommelhoff, "Electron phase space control in photonic chip-based particle acceleration," Nature 592, 498â€“502 (2021).

5. R. Shiloh, T. Chlouba, and P. Hommelhoff, "Quantum-coherent light-electron interaction in an SEM," Submitted arxiv.org/abs/2110.00764 (2021).