Driving enhanced quantum sensing in partially accessible many-body systems

Abstract

Ground state criticality of many-body systems is a resource for quantum enhanced sensing, namely Heisenberg precision limit, provided that one has access to the whole system. We show that for partial accessibility the sensing capacity of a block in the ground state reduces to sub-Heisenberg limit. To compensate for this, we drive the system periodically and use the local steady state for quantum sensing. Remarkably, the steady state sensing shows a significant enhancement in its precision in comparison with the ground state and even shows super-Heisenberg scaling for a certain range of frequencies. The origin of this precision enhancement is found to be the closing of the Floquet gap. This is in close correspondence with the role of the vanishing energy gap at criticality for quantum enhanced ground state sensing with global accessibility.

Global Sensing and Its Impact for Quantum Many-Body Probes with Criticality

“…Hence, developing these types of sensors for many particles, where the quantum enhancement becomes significant, is extremely challenging in practice. To overcome such difficulties, a plethora of novel methods and systems have been exploited for sensing purposes, including quantum control techniques [23][24][25][26], machine learning algorithms [27][28][29], hybrid variational methods [30], feedback schemes [31][32][33][34], quantum chaos [35], periodically driven systems [36,37] and sequential measurements [38][39][40][41].…”

Many-body quantum thermal machines

“…One can use ( 74)-( 78) to choose WM with appropriate critical exponents and dimensionality, so as to design optimal many-body quantum critical engines. For example, other factors remaining constant, enhancement in output power would demand a WM with large dimension d (see (74)). Furthermore, in case of free-fermionic WM operated in presence of locally thermal baths, one can also arrive at a maximum efficiency bound η max which shows universal scaling with respect to the length N of the WM, given by the relation…”

“…The many-body effects may arise due to collective coupling between a manybody system and external dissipative baths [42][43][44], or due to inter-particle interactions in a many-body system [45][46][47][48][49][50][51]. Several works have focussed on utilizing these many-body effects to design novel quantum thermal machines [42-46, 49, 50, 52-55], quantum batteries [56][57][58][59][60][61][62][63][64][65][66][67][68] and quantum probes [44,[69][70][71][72][73][74][75]. In light of the recent rapid progress in experimental studies of quantum systems, one can envisage experimental realizations of such technologies in very near future, in several existing platforms, such as those based on Rydberg atoms [76,77], ion traps [25], optical lattices [78] and nitrogen vacancy centers in diamonds [28].…”