With a special thank to @pasquans2.bsky.social, @agencerecherche.bsky.social, QuanTiP, QICS and @erc.europa.eu.

Our wok thus constitutes a key step toward genuine quantum simulation with circular Rydberg atoms. And we are quite excited about it! (14/14)

In this picture, the ancilla circular atoms stay in n=52 (small blue torus) if a nearby ancilla is in 45S (large green sphere) but it is excited to n=54 (large red torus) if the ancillae are in their ground state (small red sphere). (13/14)

We use a symmetric process to block a microwave transfer between the circular state n=52 and n=54 by exciting an ancilla atom to 45S. This effectively enables an optical control (phase flip and spin flip) of the circular Rydberg state. (12/14)

Eventually, the ancilla stays in the ground state if the circular atom is in n=54. It is excited to the 45S Rydberg level if the circular atoms is in n=52. An optical destructive measurement of the state of the ancilla then provides a quantum non-demolition measurement of the circular state! (11/14)

If we try and optically excite the ancilla to 45S, the process is impervious to the presence of a circular atom with n=52. However, if the circular atom is in n=54, the strong interaction splits the excitation line and blocks the excitation, in a usual Rydberg blockade mechanism. (10/14)

By tuning the electric field, the interaction is made resonant and strong for specific levels: the circular state with principal quantum number n=54 and the low-angular-momentum Rydberg levels 45S, in our work. If the circular atom is in another level (n=52), the interaction is negligible. (9/14)

In this work, we make circular Rydberg atoms (blue torus in the picture) interact with other atoms initially in their ground state (red spheres) and excited to low-angular-momentum Rydberg levels. All atoms are laser trapped in the experiment. (8/14)

But these operations are key to quantum simulators! They enable the initialization of the simulator (prepare the atoms in different states) or the measurement of the final state of the simulator (measure the state of every atom). (7/14)

The long lifetime of circular Rydberg atoms stems from the absence of optical transition from or to circular levels. The counterpart is that these levels are hard to detect (no direct fluorescence imaging) or to optically manipulate. (6/14)

They can also be laser trapped in so-called optical bottle beams, that present a local minimum of intensity. (5/14)

Circular Rydberg atoms have the key asset to have a natural lifetime 100 times longer than that of the low-angular-momentum Rydberg levels. This makes them particularly appealing for quantum simulation of the dynamics of interacting spins, in particular slow dynamics such as thermalization. (4/14)

Low-angular-momentum Rydberg levels are typically used in quantum simulation and computation because they can be optically excited from the ground state. Arrays of atoms, which interact together when excited to Rydberg levels, simulate, for instance, quantum magnetism. (3/14)

In this work, we propose and demonstrate a novel hybrid platform where circular Rydberg atoms are measured and manipulated through their coupling to ancilla atoms, transiently excited to a more common low-angular-momentum Rydberg level. (2/14)