Quantum technologies come in a wide variety of forms, from computers, sensors, and cryptographic systems to simulations and imaging systems. But one thing that all current and future quantum systems have in common is the need to achieve reliable control over physical systems such as atoms or photons. A frequently used method to prepare quantum systems in the desired quantum state is a quantum adiabatic process, but these processes often take so long that environmental noise causes the quantum state to decohere and lose its “quantumness.”
To speed up quantum state preparation and minimize decoherence, physicists have devised so-called “shortcuts to adiabaticity” (STA), which refer to any process that prepares quantum states in a shorter time than adiabatic processes without losing the benefits of being adiabatic. Originally developed for simple systems consisting of a single particle, STA has recently been extended to many-body systems, which are more relevant for applications. However, the implementation of STA in many-body systems is still very challenging due to the inherent complexity of these systems.
Researchers have devised a new hybrid method for preparing quantum states for many-body systems that combines STA with optimal control. The main advantage of the new method is that it can achieve nearly perfect STA performance yet allows for significant simplification by not requiring complete knowledge of the underlying mechanisms. The method shows that it’s possible to speed up quantum state preparation at a low enough cost to justify the quantum shortcut.
We study transitionless quantum driving in an infinite-range many-body system described by the Lipkin-Meshkov-Glick model. Despite the correlation length being always infinite the closing of the gap at the critical point makes the driving Hamiltonian of increasing complexity also in this case. To this aim we develop a hybrid strategy combining shortcut to adiabaticity and optimal control that allows us to achieve remarkably good performance in suppressing the defect production across the phase transition.
SOURCE – Arxiv, Phys Org