Superfluidità in onda p in miscele eteronucleari di litio e cromo ultrafreddi


Funded by: Ministero dell’Istruzione, Università e Ricerca (MIUR)  
Calls: FARE Ricerca in Italia
Start date: 2018-01-01  End date: 2020-12-31
Total Budget: EUR 116.610,00  INO share of the total budget: EUR 116.610,00
Scientific manager: Zaccanti Matteo   and for INO is: Zaccanti Matteo

Organization/Institution/Company main assignee: CNR – Istituto Nazionale di Ottica (INO)

other Organization/Institution/Company involved:

other INO’s people involved:

Abstract: Topological superfluids and superconductors are among the most intriguing many-body states in contemporary physics.
In two dimensions, their topological properties are fundamentally connected to fractional quantum Hall states featuring non-Abelian excitations with promising applications in quantum computing.
However, topological superconductivity/superfluidity in electronic matter and 3He remain highly debated as their realization and probing is extremely challenging.
In fact, p-wave pairing in such systems is easily overcome by other competing phases.
For instance, the elusive A-phase of 3He emerges only at low temperature and high pressure close to solidification.
Similarly, Sr2RuO4 and UGe2 turn superconductors at temperatures much lower than the Curie temperature, on the border of itinerant ferromagnetism.
Owing to the fragile nature of such phases and to the anisotropic nature of the associated pairs, they are extremely sensitive to impurity scattering that causes pair breaking.
Although new systems are being developed, advanced material engineering is required, and the prospects for probing exotic topological phases would be greatly enhanced if they could be realized in systems that were easily tuned.
This has triggered a growing interest in ultracold atom-based platforms to investigate unconventional p-wave pairing, including Fermi gases near a p-wave Feshbach resonance, spin-orbit coupling and dipolar systems.
Although impressive progress in the field, at present inelastic processes limit the lifetime of these systems, and p-wave superfluidity lacks experimental observation in the ultracold regime.
In P-HeLiCS unconventional superfluidity will be investigated both theoretically and experimentally on a conceptually new framework realized by a Fermi mixture of ultracold Lithium and Chromium atoms in the regime of strong attraction near an s-wave scattering Feshbach resonance.
The existence of a quasi-bound three-body Cr-Cr-Li state with p-wave character above the three-atom collision threshold enables for the first time to engineer a strong p-wave attraction between identical Cr fermions, mediated by the surrounding Lithium atoms.
Importantly, such a non-perturbative effective p-wave coupling can be resonantly enhanced in experiments via tuning an external magnetic field, and it features a purely elastic character.
As such, p-wave superfluid pairing of Cr atoms can develop at high critical temperatures without being affected by detrimental decay processes.
The thorough investigation of the phase diagram of the system will be theoretically tackled via diagrammatic and Monte Carlo approaches.
Experimentally, this will be accomplished by employing state-of-the-art techniques and spanning the temperature, interaction and population imbalance of the mixture. The success of P-HeLiCS will provide new fundamental insights into topological superfluidity within a robust and simple platform.

The Scientific Results:
1) Time-Resolved Observation of Competing Attractive and Repulsive Short-Range Correlations in Strongly Interacting Fermi Gases