The main concepts behind SE

The new vision behind SE

The wave nature of light has enabled the development of several tools to shape it into new wave structures characterised by non-trivial spatio-temporal properties. Beyond traditional lenses, spatial light modulators (SLM) and metamaterials have revolutionized optics by enabling efficient control of electromagnetic fields in new and unexpected ways, leading to significant impact in both fundamental and applied science such as the development of super-resolved optical microscopies. 

The vision behind the SMART-electron project is to establish a novel technological paradigm that exploits the power of control reached with light to coherently shape electron matter waves, revolutionizing the way materials are investigated in electron microscopy. This will grant us access into new phenomena benefiting from interaction with the electron charge and with a spatial accuracy at least three orders of magnitude better than what is currently achievable in light optics.

Spatial and temporal shaping of electron beams could provide new routes toward image-resolution enhancement, selective probing, low-dose imaging, faster acquisition, depth information, and high temporal and energetic resolutions. 

Going beyond current paradigms

Reaching this new vision requires, however, a radical departure from current electron microscopy schemes, which so far rely on passive static modulation of the electron wave function using monolithic phase masks, such as spiral plates and holograms, or slowly-varying electrostatic and magnetostatic displays (milliseconds or longer). 

In SMART-electron, we will pursue a disruptive approach for coherent and arbitrary dynamical shaping of the electron wave properties down to the femtosecond range and below, many orders of magnitude faster than conventional schemes.

This will open new frontiers not only in microscopy but also in optoelectronics, quantum information and biosensing. To reach the required high speed, flexibility and precise phase control needed to make such potential a reality, we introduce a new paradigm where properly synthesized ultrafast light fields will be used for engineering the electron phase space.

SE technological breakthrough

SMART-electron aims at developing an innovative technological platform for designing, realizing and operating all-optical rapidly-programmable phase masks for electrons.

These would rely on a light-mediated coherent modulation of the longitudinal and transverse phase of an electron wave function, exploiting the strong interaction between free electrons and optical fields in illuminated nanostructures. 

The fast, arbitrary, and versatile control achievable with such ultrafast light fields would allow us to dynamically manipulate the spatial, temporal, energetic, and momentum distributions of an electron in a coherent and correlated manner. The main idea is that a simultaneous time-varying and spatially-varying phase modulation, as induced by quantized energy-momentum exchanges between the electron and the driving optical field, will lead to significant non-conservative forces that result in a strong modification of the electron group velocity profile. 

The extremely fast control and the highly versatile manipulation, together with the ability to couple longitudinal and transverse phase shaping, are unattainable features with existing monolithic phase masks or electrostatic displays, allowing us to access a completely unexplored range of the phase space. This is what makes our Photonic-based free-ELectron Modulators (PELMs) unique with respect to current schemes. SMART-electron has a clear technological outcome and a powerful strategic objective. The technological outcome is, as mentioned above, the development of a photonic modulator for dynamic multidimensional control of electrons. To carry out this objective, we will use advanced theoretical and experimental methods enabling precise modelling, design, and characterization of the light-induced electron phase shaping. This will be instrumental to the following design and practical realization of such photonic modulators. 

SE strategic objectives

The strategic objective of SMART-electron will be the ability to radically change how materials are investigated in electron microscopy, in particular leading to unprecedented visualization of entangled states in quantum systems, real-time electrochemical reactions, and biomimetic nanoparticles in cells for drug delivery. 

To achieve this objective, we will implement three new beyond-the-state-of-the-art electron imaging techniques enabled by such superior electron phase control. The first one is a Ramsey-type Holographic Imaging for disentangling the contribution of hybridized low-energy modes in strongly-correlated systems, which is a long-standing issue of key importance for their technological implementation. The second one is an Electron Single-Pixel Imaging method that has been only recently proposed for optical detection and now, using PELMs, would become possible also in electron microscopy. This will permit lower electron doses, faster acquisition rates and more reliable 3D imaging of nanoscopic objects in their natural environment, which are key features for the investigation of transport of Lithium ions during a battery operation. The third one is a Quantum Cathodoluminescence scheme based on an enhanced light emission when materials are interrogated with structured free-electron waves, allowing unprecedented spatio-temporal localization of nanoparticles in cells for drug delivery and nanomedicine applications. 

By boldly surpassing the current paradigms of electron manipulation, the project, which is feasible yet groundbreaking, has the potential to drive electron microscopy into a new and exciting age where scientists will benefit from new tools with unprecedented performances that were unimaginable until now.