EPSRC Reference: 
EP/Y015363/1 
Title: 
QUantum Emergent Hydrodynamics of integrable manybody Systems : from Theory to applications and experimental validation (QuEHST) 
Principal Investigator: 
Ruggiero, Dr P 
Other Investigators: 

Researcher CoInvestigators: 

Project Partners: 

Department: 
Mathematics 
Organisation: 
Kings College London 
Scheme: 
New Investigator Award 
Starts: 
01 April 2024 
Ends: 
31 March 2027 
Value (£): 
333,136

EPSRC Research Topic Classifications: 
Cold Atomic Species 
Condensed Matter Physics 
Quantum Optics & Information 


EPSRC Industrial Sector Classifications: 
No relevance to Underpinning Sectors 


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Panel History: 

Summary on Grant Application Form 
Quantum physical systems consisting a large number of particles are difficult to study: this is well known in the context of statistical physics, whose "holy grail" is to understand the emergent behaviour of such systems starting from the microscopic models.
When manybody systems are probed at distances and time scales 'large enough' (at mesoscopic scales), their emergent and rather complex behaviour is well described by hydrodynamics. The latter can be described as the observation that the motion of many interacting particles is constrained by local conservation laws: the hydrodynamic equations, in fact, are basically continuity equations relating density and current density associated with the conserved quantities themselves.
While for generic systems with a few conserved quantities (tipically energy, momentum and number of particles), this is known since a long time, a similar hydrodynamic framework was only recently unveiled for systems possessing infinitely many of such conservation laws, i.e., integrable models (known for escaping standard thermalization to the Gibbs ensemble). This theory is known as Generalized Hydrodynamics (GHD).
But, how 'quantum' are the current hydrodynamic descriptions of quantum systems? In fact, the local relaxation assumption implies quantum decoherence among different fluid cells and, therefore, notably, the loss of equaltime longrange quantum correlations among the fluid cells (including zero entanglement).
From there, the necessity to requantize such theories, and in particular, of relevance for us, GHD. This is what we achieved in 2020, by establishing the theory of Quantum Generalized Hydrodynamics (QGHD).
This framework already proved able to give, in an elegant and simple fashion, nontrivial analytic predictions for quantities which were, before, thought inaccessible, especially in the case of fully interacting models. Still, it is relatively new, and therefore there are many open questions calling for an answer. This challenge is the starting point of this proposal, aiming at exploring different directions, ranging from theory to applications and experimental validation of the theory itself.

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