Multiparameter quantum critical metrology

Fresco, Giovanni Di; Spagnolo, Bernardo; Valenti, Davide; Carollo, Angelo

doi:10.48550/arxiv.2203.12676

Cited by 1 publication

(2 citation statements)

References 65 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although we consider only the probe Hamiltonian explicitly here, we take the fermionic leads implicitly and assume thermalization has occurred. The reduced states of the probe are therefore equivalent to the isolated probe states, and we can use the exact populations ϱ i obtained in equations ( 17) and (18) to calculate the single-parameter QFI for estimation for T or K by using equation (19). In this limit we find for thermometry,…”

Section: Large K-limitmentioning

confidence: 99%

“…However, GHZ-based quantum sensors are hard to scale up and are prone to decoherence [5,6] and perturbation [7]. Alternatively, strongly correlated quantum many-body systems near their phase transitions have been identified as a resource for quantum enhanced sensitivity [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Several kinds of phase transitions have been proposed for quantum sensing, including second-order [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40], topological [41][42][43][44][45], superradiant and Rabi type [46][47][48][49][50][51][52]…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Multiparameter critical quantum metrology with impurity probes

Mihailescu,

Bayat,

Campbell

et al. 2024

Quantum Sci. Technol.

View full text Add to dashboard Cite

Quantum systems can be used as probes in the context of metrology for enhanced parameter estimation. In particular, the delicacy of critical systems to perturbations can make them ideal sensors. Arguably the simplest realistic probe system is a spin-1/2 impurity, which can be manipulated and measured in-situ when embedded in a fermionic environment. Although entanglement between a single impurity probe and its environment produces nontrivial many-body effects, criticality cannot be leveraged for sensing. Here we introduce instead the two-impurity Kondo (2IK) model as a novel paradigm for critical quantum metrology, and examine the multiparameter estimation scenario at finite temperature. We explore the full metrological phase diagram numerically and obtain exact analytic results near criticality. Enhanced sensitivity to the inter-impurity coupling driving a second-order phase transition is evidenced by diverging quantum Fisher information (QFI) and quantum signal-to-noise ratio (QSNR). However, with uncertainty in both coupling strength and temperature, the multiparameter QFI matrix becomes singular -- even though the parameters to be estimated are independent -- resulting in vanishing QSNRs. We demonstrate that by applying a known control field, the singularity can be removed and measurement sensitivity restored. For general systems, we show that the degradation in the QSNR due to uncertainties in another parameter is controlled by the degree of correlation between the unknown parameters.

show abstract

Section: Large K-limitmentioning

confidence: 99%