Building a superconducting quantum circuit that follows protons on the go

Amazing stuff!

"Researchers ... have created a device that simulates the quantum “tunneling” behavior of protons that occurs in chemistry, a process so common it occurs in everything from photosynthesis to the formation of human DNA.

The advance has the potential to aid researchers across a variety of disciplines, including the development of new solar fuels, pharmaceuticals, and materials. ...

“Our system is so clean and controllable that we could resolve very subtle quantum tunneling effects with it that were unknown to us,” ..."

From the abstract:

"Dissipative tunneling remains a cornerstone effect in quantum mechanics. In chemistry, it plays a crucial role in governing the rates of chemical reactions, often modeled as the motion along the reaction coordinate from one potential well to another. The relative positions of energy levels in these wells strongly influence the reaction dynamics. Chemical research will benefit from a fully adjustable, asymmetric double-well equipped with precise measurement capabilities of the tunneling rates.

In this paper, we show a quantum simulator system that consists of a continuously driven Kerr parametric oscillator with a third-order nonlinearity that can be operated in the quantum regime to create a fully tunable asymmetric double-well. Our experiment leverages a low-noise, all-microwave control system with a high-efficiency readout, based on a tunnel Josephson junction circuit, of the which-well information.

We explore the reaction rates across the landscape of tunneling resonances in parameter space. We uncover two counter-intuitive effects:

(i) a weak asymmetry can significantly decrease the activation rates, even though the well in which the system is initialized is made shallower, and

(ii) the width of the tunneling resonances alternates between narrow and broad lines as a function of the well depth and asymmetry.

We predict by numerical simulations that both effects will also manifest themselves in ordinary chemical double-well systems in the quantum regime.

Our work is a first step for the development of analog molecule simulators of proton transfer reactions based on quantum parametric processes."

Building a superconducting quantum circuit that follows protons on the go | Yale News "A new device that originated at a pair of Yale labs simulates quantum proton “tunneling,” a ubiquitous phenomenon found commonly in chemistry and biology."

Asymmetry Control in a Parametric Oscillator for the Quantum Simulation of Chemical Activation (open access)

Fig. 1 Experimental setup. (a) Rendering of the half-aluminum, half-copper sample package containing two sapphire chips magnified in (b).