Session S02: Going Beyond the Qubit

Quantum computation and simulation with large-ion crystals and dual-type qubits

In this talk, I will show how to realize large ion crystals for quantum simulation and computation, how to quantum simulate the Rabi-Hubbard model beyond the classical simulation capability, and how to realize dual-type qubits with the same species of trapped ions for fault-tolerant quantum error correction so that one-type of qubits can be repeatedly measured with no detrimental influence on the other-type of qubits that carry the computational information.    

Tapping into hidden resources in trapped atom quantum processors

When employing atoms for quantum information (QI) applications, it is often tempting to abstract them into faceless qubits with two (and only two) levels.  However, despite the early and frankly understandable belief that complex atoms are too unwieldy to pursue seriously for hosting qubits, we have reached a point where building QI platforms from multilevel atoms is feasible.  I will discuss some of the ways we have begun to utilize metastable beyond-qubit states in trapped ion qubits and how those capabilities can boost the capabilities of existing trapped-atom-based quantum processors and simulators.   

Quantum Simulation and Quantum Computation with Strings of Trapped Ca+ Ions

The state-of-the-art of the Innsbruck trapped-ion quantum computer is briefly reviewed. We present an overview on the available quantum toolbox and discuss the scalability of the approach. With 20-50 fully controlled ion qubits we perform quantum simulations investigating quantum transport [1] and emerging hydrodynamics features [2]. Employing the quantum toolbox for entanglement-enhanced Ramsey interferometry, we find optimal parameters for quantum metrology [3]. Quantum computers can be protected from noise by encoding the logical quantum information redundantly into multiple qubits using error-correcting codes. Manipulating logical quantum states by imperfect operations requires that all operations on the quantum register obey a fault-tolerant circuit design to avoid spreading uncontrolled errors. We demonstrate a fault-tolerant universal set of gates on two logical qubits in the trapped-ion quantum computer [4].

 

 

[1] C. Maier et al., Phys. Rev. Lett. 122, 050501 (2019)

[2] M. K. Joshi et al., arXiv:2107.00033 (2021)

[3] C. D. Marciniak et al., arXiv:2107.01860 (2021)

[4] L. Postler et al., arXiv:2111.12654 (2021)   

Towards qutrit and qudit manipulations with trapped Ba+ ions

Multi-level qudits have many potential applications in quantum simulation and quantum computation, and are relatively underexplored compared to the well understood trapped ion qubits. Ba+ ions, including the rare radioactive isotope Ba-133+, are a promising candidate to host qutrits or qudits. In this talk I will present our group's progress toward implementing a state-measurement protocol on a Ba+ qutrit, and describe the optical infrastructure required for full qutrit and qudit manipulations. I also touch on our developments with regards to producing more robust atomic sources for Ba-133+.