In summary: Nuclear spins in diamond are promising candidates for quantum technologies due to their long coherence times. The key to quantum diamond applications is the nitrogen vacuum center in the crystal that gives access to both nuclear and electronic spins. Milos Nesladek’s team at IMO – IMOMEC has succeeded in the electrical reading of the entangled nuclear electron spin At room temperature, this is important for device scaling and integration as well as applications such as ambient sensing. , has a proven track record of using synthetic diamonds in the race to develop the best solid-state quantum system. In a paper recently published in Nature Communications, they demonstrate a viable approach for a room-temperature quantum technology platform via electrically readable electronic and nuclear spin gates on a diamond electronic chip. This proof of concept is a first step towards more complex and electrically readable gating of advanced quantum technologies that can take advantage of the long nuclear spin coherence in diamond. Nuclear and electronic spins in diamond quantum systems Semiconductor spin qubit systems are promising candidates for future quantum technologies, such as quantum computing, communications and sensing due to their potential for electronic scaling and integration of nanoscale devices. Nuclear cycles in diamond are particularly interesting because of their large coherence times which is important for the performance and reliability of complex quantum applications. At ambient temperatures the cohesion time is on the order of seconds; When it cools down to about 10 kilos, it increases to tens of minutes. Milos Nesladek: “The key to quantum applications of diamond is the nitrogen vacancy (NV) center, a defect in a crystal in which a nitrogen atom replaces one of the adjacent carbons of an empty (vacancy) lattice space. The negatively charged NV center is one of the most attractive solid qubit platforms because it takes advantage of An electronic spin that can be used as a qubit or as a qubit helper to read dark nuclear spins.Access to both electron and nuclear spin (nitrogen) offers many advantages as they perform different functions.Electron cycles have shorter coherence times but provide fast control, while more nuclear spins can be used stable, for example, as a qubit memory to store spin information from an electronic qubit.An optical table with a room temperature quantum microscope setup used in a single nuclear spin reading experiment.The two qubits can also be entangled.Entanglement is a fundamental quantum process that enables quantum computers, it is It reduces the time to transfer information between qubits and is ultimately necessary for many other quantum applications such as quantum communication. Quantum entanglement mainly serves at extremely low temperatures, close to absolute zero. Electrical readings at room temperature Currently, nuclear and electron spin entanglement is read optically using huge setups. Milos Nesladek: “We are interested in reading spin states electrically, because it will open access to miniaturization and integration of electronic devices with many modular electron and nuclear spin units entangled on a single electronic quantum chip. These units can communicate in two ways. First, one can place them close to each other. , usually at less than 50 nm, but then cannot be resolved optically due to the diffraction limit of the optics. This poses a problem to operate the modules individually and to use entangled quantum gates. To circumvent this, we fabricated electrical contacts around the NV centers in the modules, allowing the modules to be read individually.” “With electrical readouts, spatial resolution is determined only by electrode size which opens the way for placing spin qubits in very close proximity and ultimately for fabricating nanoscale quantum systems with scalability in semiconductors. It has been successfully used to measure the spin state of large groups of Nuclear spins recently, but basic quantum processes depend on driving and reading single qubits.Here, we show the electrical readings of a single nuclear spin of an NV center, Bos One electron spin,” Milos Nesladek says. Moreover, we show it at room temperature. One advantage of these qubits is their ability to operate at ambient temperatures. The nuclear spin coherence time at these high temperatures is still in the range of seconds. For certain quantum processes, we will also cool them down to tens of Kelvin but not to the same extent in the classical system that targets temperatures close to absolute zero in the milliKelvin range. Enabling quantum processes at higher temperatures has a huge impact on quantum computer systems in the future as cooling systems consume a huge amount of energy and are currently one of the constraints to expansion.” Details showing the routing of the 532nm laser beam used for spin polarization and reading NV. The beam is directed to a quantum chip consisting of a diamond plate with electrical contacts and MW tape lines for spin state processing (not shown). Applications and quantum arrays “Diamond-based qubits are unbeatable as room temperature sensors for example for magnetic/electric field, temperature, or particles.” If we sense tangles, we can increase their sensitivity. For quantum computing applications, which typically require thousands of qubits, diamond qubits still face some obstacles. The challenge is to inevitably produce NVs with high probability. Currently, we can generate them with ~90% probability, but that number drops to ~65% when creating 4. If you go into the thousands, the probability is very slim… to solve this will require more research on all fronts, from materials to electronics to The complete system.” Milos Nesladek: “We have now succeeded in demonstrating electrically readable entangled qubits. The next step is to take advantage of the scalability of the electron core unit and create arrays. We are working on a chip with 4 NV cores, separated by 50 nm. If we can stably connect these 4 qubits to the 5 nuclear windings, we have access to a 20-qubit system which can operate at reasonably low temperatures (about 10K or higher). Then it becomes very interesting for many new applications, such as quantum simulators! Want to know more? Read more details about the work of the Milos Nesladek team in two recent papers that can be requested via this link (https://www.imec-int.com/en/about-us/imec-magazine/contact-form-imec -Journal): Gulka et al. Room temperature control and electrical readout of nitrogen-free nuclear spin Nature Communications 12:4421, 2021. Syushev et al. Photoelectric imaging and spin-state coherent reading of single nitrogen vacancy centers in diamond Science, 363:728- 731, 2019. Background information on diamond research at IMO-IMOMEC can be found here https://www.imec-int.com/en/imec-magazine/imec-magazine-may-2019/the – The potential of synthetic diamond heads Drilling into Quantum Sensors CV Prof. Milos Nesladek received his MSc degree from the Faculty of Mathematics and Physics, Charles University in Prague, and his PhD from Czech Academic Sciences, in collaboration with KU Leuven in the field of electronic transport in semiconductors.He is a professor of physics at Hasselt University and a faculty member of IMO-IMOMEC, an i . research group mec at Hasselt University. He is one of the pioneers in the field of CVD diamond crystal growth in all its forms, having worked in the field for the past 30 years. Prof. Nesladek’s research topic deals with optical conduction in condensed matter systems with a focus on wide bandgap semiconductors. An example of this research is the development of solid-state Q-bits for ferroelectric reading in diamond based on magnetic spin centers. Professor Nesladek has been involved in a large number of EU projects ranging from basic physics to industrial development projects, some of which he has coordinated. Professor Nesladek is a member of several conference boards and is the Belgian representative in Quantum Flagship’s Quantum Society Network (QCN). Professor Nesladek has published more than 300 scientific papers and contributed to many books. He is Associate Editor of Diamond Related Materials. Professor Milos Nesladek.