The quantum computer microscope
A new invention is set to significantly improve electron microscopy
electron microscopes are used wherever particularly small details need to be imaged. But from a strictly physical point of view, every electron in a conventional electron microscope represents a missed opportunity: if all you do is count electrons, any additional quantum information they carry remains unused.
An electron microscope capable of performing quantum computing operations using built-in ion traps
© TU Wien
A team at TU Wien, together with teams from the University of Vienna, JKU Linz and the University of Innsbruck, has now developed a way to make use of the quantum information carried by electrons in an electron microscope: the electron beam is coupled to a quantum computer, opening up entirely new possibilities for working with the quantum information of the electrons. This is particularly important for sensitive samples that cannot be bombarded with arbitrarily large numbers of electrons. The quantum-computer electron microscope is now being built at TU Wien.
Controlled Quantum Entanglement
The resolution that can be achieved with modern electron microscopes is remarkable: “Today, we can image tiny details on the atomic scale,” says Philipp Haslinger from the Institute of Atomic and Subatomic Physics at TU Wien. “However, this requires a large number of electrons. And not every sample can be exposed to so many electrons without being damaged. This is often a problem, particularly when imaging biological samples such as individual proteins.”
If, however, more information can be extracted from each individual electron than before, a smaller number of electrons is sufficient. The team has now found a method to achieve precisely this: “Our idea is to combine the electrons with a quantum computer. We let them interact with ions that are held in place along the path of the electron beam,” explains Elias Pescoller, first author of the publication and a doctoral student at the Institute for Theoretical Physics and the Institute of Atomic and Subatomic Physics at TU Wien. “This can, for example, create quantum entanglement between the electron and the quantum computer. The electron and the ion then share a joint quantum state.”
A Clearer Signal Than Classical Physics Allows
The ion in the quantum computer now carries information about the electron – and shortly afterwards, the next electron passes by and is likewise entangled with the quantum computer. “If we perform very specific quantum-computing operations each time, we can optimally combine the information from several electrons so that we obtain a signal of maximum strength even though we use only a relatively small number of electrons,” says Dennis Rätzel from the Institute of Atomic and Subatomic Physics at TU Wien. The algorithms that make this possible were developed in collaboration with Johannes Kofler’s team at JKU Linz.
“The electrons themselves are used to image small objects, just as in any other electron microscope. But by processing the quantum information carried by these electrons in a quantum computer, we can extract significantly more information from the process,” says Iva Březinová from the Institute for Theoretical Physics at TU Wien. “What would previously have been indistinguishable from random noise can thus become a clear signal.”
Quantum physics offers possibilities here that are fundamentally unattainable without quantum effects, using purely classical electron counting. “Quantum physics allows us to overcome the statistical limits that constrain conventional electron microscopes,” says Elias Pescoller.
Next Step: Experiments
The team was able to demonstrate mathematically the advantages offered by the new method. The next step is experimental implementation: at TU Wien’s University Service Centre for Transmission Electron Microscopy (USTEM), an ion-based quantum computer developed by Philipp Schindler’s team at the University of Innsbruck is now to be integrated into an electron microscope.
“It is really exciting that, within the quantA Cluster of Excellence, we can combine the expertise in quantum information, quantum computing and electron microscopy available at the different universities in Austria. This allows us to launch a unique project,” says Thomas Juffmann from the University of Vienna.
Original publication
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