Sakshee Patil

Quantum simulation of open quantum systems offers a pathway towards better understanding various non-equilibrium physics that would otherwise be challenging to study. Most open quantum systems studied are modeled as obeying the Markov approximation, where the bath into which the system dissipates information is assumed to be unaffected by the system-bath interaction. However, real baths are in general influenced by this interaction to some degree, and some systems which exist in structured non-Markovian environments can display novel behavior as a result. Here we utilize a trapped ion quantum simulator to simulate a single spin-$1/2$ driven-dissipative system with a non-Markovian dissipation channel, and experimentally compare steady-states to those from an analogous Markovian bath. We observe that a non-Markovian dissipative channel can dramatically change the steady-state even for a single qubit, to a regime inaccessible for Markovian dissipation. This demonstrates the added richness available to quantum systems in structured environments. The techniques used here are compatible with many-body extensions of the model, which can not be simulated efficiently on a classical computer in general. Our work also opens up new possibilities in quantum reservoir engineering beyond the Markovian regime.

We present a room-temperature Extreme High Vacuum (XHV) system engineered to support the long-duration operation of a trapped-ion quantum processor. Background-gas collisions impose limitations on trapped-ion performance and scalability by interrupting algorithmic execution and, in some cases, ejecting ions from the trap. Using molecular-flow simulations, we optimize the chamber geometry, conductance pathways, and pumping configuration to maximize the effective pumping speed at the ion location. We perform high-temperature heat treatment of stainless steel vacuum components to achieve the desired outgassing rate, guided by quantitative relations of bulk diffusive processes, allowing us to reduce the \(\mathrm{H_2}\) outgassing load to the \(10^{-15}\,\mathrm{mbar\,l\,s^{-1}\,cm^{-2}}\) level. The final pressure in our chamber, measured by a hot cathode gauge, is \(1.5\times10^{-12}\,\mathrm{mbar}\), corresponding to the gauge's measurement limit. We measure the local pressure at the ion location by observing collision-induced reordering events in a long ion chain of mixed-isotope Yb\(^+\). From the observed reordering frequency, we extract the average interval between collisions to be \((1.9 \pm 0.1)\,\mathrm{hrs/ion}\). This corresponds to a local pressure of \((3.9 \pm 0.3)\times10^{-12}\,\mathrm{mbar}\) at the ion location, assuming that all collisions arise from background H\(_2\) molecules at room temperature. Our demonstration extends the continuous operation time of a quantum processor while maintaining the simplicity of a room-temperature system that does not require cryogenic apparatus.