Strontium Lab

We present a detailed experimental study on the ultranarrow magnetic-quadrupole transition from the ground state to the ³P₂ metastable state in neutral strontium. Although this transition is one of the key components of proposed quantum computing and quantum simulation schemes with neutral alkaline-earth atoms, no precise experimental data for its properties is available so far. The ³P₂ state offers a magnetic-field-insensitive Zeeman sublevel, which, together with the ground state, forms an optical qubit. In addition, a magnetic field-sensitive sublevel is available enabling single-site addressing in an optical lattice within a magnetic field gradient which is of high interest for quantum simulation and computation. We demonstrate the first narrow-line optical spectroscopy of this transition in neutral strontium by suppressing Doppler broadening and light shifts in an light-shift-engineered optical lattice. This engineered potential allows us to measure for the first time the absolute frequency of the transition in the bosonic isotope ⁸⁸Sr with kilohertz precision. Furthermore, we measure the ⁸⁸Sr to ⁸⁷Sr isotope shift, and reduce the uncertainty of the absolute transition frequency in ⁸⁷Sr by two orders of magnitude. In addition, we experimentally verify that the transition has quadrupole character and create an intuitive understanding for the absorption pattern. As a proof of principle application, we demonstrate single-site spatial addressing in our optical lattice in the presence of a magnetic field gradient.

Have a look at our preprint on the Physics arXiv.

Sebastian Pucher just joined our group as a Postdoc. Welcome Sebastian!

Felix Spriestersbach just joined our group as a PhD student. Welcome Felix!

Ömer Faruk Erşahan just joined our group as a Masters student. Welcome Ömer!

Our paper Cavity-Enhanced Optical Lattices for Scaling Neutral Atom Quantum Technologies to Higher Qubit Numbers was just published in PRX Quantum.

As usual, the paper is also available on the Physics arXiv.

Andreas Meyer just joined our group as a Masters student. Welcome Andreas!

Annie just defended her PhD thesis at LMU Munich and will start her new position as a postdoc in the Ni group in Spring 2022. Congratulations Annie!

We have been funded by the Bavarian state to build a lab-scale quantum computer based on ultracold strontium atoms trapped in optical lattices. Our new team is responsible for one of three technology pillars of the Munich Quantum Valley. Interested? Check out our new webpage for more information and apply!

We describe a new architecture for scaling up neutral-atom quantum technologies based on our recently developed crossed optical resonators. As a proof-of-principle, we trap strontium atoms in two-dimensional optical lattices created by these monolithic, in-vacuum resonators, and show that the lattices are an order of magnitude larger than state-of-the art free-space lattices. We observe ground-band and lattice lifetimes of 18 s and 60 s, respectively, demonstrating that there are no disadvantages of our approach compared to free space, while allowing the creation of deep optical lattices at wavelengths where the available laser power is limited. We use high-resolution laser spectroscopy to characterize the optical potential with 300 ppm precision. In addition, the method allows us to precisely measure the relative polarizability of both clock states, and to locally measure the sample temperature with a spatial resolution limited only by the imaging system resolution. Our results lay out a roadmap to scaling optical lattice clocks, quantum simulators, and quantum computers to tens of thousands of qubits.

Have a look at our preprint on the Physics arXiv.

If you are interested in the long-term goals of our work at the Max-Planck-Institute of Quantum Optics, you should check out our new outreach article, written in an accessible form. Typical projects in our field take a long time to realize because we need to develop the necessary quantum technology, so it useful to recall once in a while what it is that we’re shooting for.

Dimitry Yankelev just joined our group as a Postdoc. Welcome Dimitry!

Our paper Crossed optical cavities with large mode diameters was just published in Optics Letters.

As usual, the paper is also available on the Physics arXiv.