TRENSCRYBE proposes a new concept for a quantum simulator of spin systems based on laser-trapped "circular Rydberg atoms". It aims at an in-depth understanding of many-body physics of importance for fundamental issues (quantum transport, quantum phase transitions) and for applications to engineering of new quantum materials. A quantum simulator, as originally proposed by Feynman, aims at synthetizing a quantum system with the same properties as an existing material but with an increased degree of control of physical parameters and offering an experimental access to microscopic observables such as the detailed quantum state of each individual particle. As exact numerical simulations are beyond the reach of classical computers as soon as the system contains more than a few tens of particles, one expects quantum simulators to be a promising alternative route for exploring many-body quantum phenomena.
Moreover, a quantum simulator could also be used to efficiently solve a general class of optimization problems, that can be formulated as the determination of the ground-state of a complex many-body system with tunable interactions. As such, a quantum simulator appears as a realistic and promising route for the development of quantum technologies with an important societal impact.
Our objective consists in performing quantum simulations based on a collection of laser-trapped "circular Rydberg atoms". Rydberg atoms have one of their valence electrons promoted to a highly excited state, close to the ionization limit. Quantum simulators based on the manipulation of up to about 256 laser-accessible low-angular-momentum Rydberg atoms already operate. However, the timescale of these experiments is limited to a few microseconds only, due to the finite radiative lifetime of low-angular-momentum Rydberg states. Instead, Rydberg atoms with maximal angular momentum, so called "circular atoms", whose lifetime of tens of millisecond could be used to extend the range of simulation timescales from microseconds to hundreds of microseconds.
At the end of the project, we achieved the construction of a Rydberg atom quantum simulator involving up to 20 individually trapped circular Rydberg atoms of rubidium. In parallel we developed two other projects aiming on the long term at overcoming the limits of the present rubidium platform. The first project aims at further increasing the accessible timescale of quantum simulations by increasing the lifetime of circular atoms from tens of milliseconds to more than one minute by using a spontaneous emission inhibition structure.
The second project consists in the construction of a second circular atom-based quantum simulation platform using strontium, which is a two valence electrons atom. Once one valence electron is promoted to a circular state, the second one can still be optically excited offering new possibilities for trapping, cooling or manipulating quantum superpositions of circular states. In particular, the possibility to cool down the initial motional state of an atom once it is in a circular state and the perspective of an optical detection of individual circular atoms are of particular interest for circular atom-based quantum simulators. At the end of the project, we have implemented preliminary experiments on circular sates of strontium using a fast atomic beam. A cryogenic version of the experiment involving trapped ultracold circular strontium was designed and is presently in construction.
