We analyze an efficient frequency estimation scheme that is applied to measure the unknown frequency of an atomic state in Ramsey spectroscopy. The scheme is employing appropriate combinations of uncorrelated probe atoms and Greenberger–Horne–Zeilinger (GHZ) type correlated probe atoms to estimate its frequency. The estimation value of frequency is obtained through the Bayesian analysis of the final measurement outcomes. The proposed scheme allows us to obtain better precision than the scheme without quantum correlation and it also prevents us from ambiguity in the frequency estimation procedure with GHZ correlations only. We show that the scheme can beat the shot-noise limit and, in addition, it is found that there is a trade-off relation between the precision of the frequency estimation and the decoherence rate in the atomic states.We analyze an efficient frequency estimation scheme that is applied to measure the unknown frequency of an atomic state in Ramsey spectroscopy. The scheme is employing appropriate combinations of uncorrelated probe atoms and Greenberger–Horne–Zeilinger (GHZ) type correlated probe atoms to estimate its frequency. The estimation value of frequency is obtained through the Bayesian analysis of the final measurement outcomes. The proposed scheme allows us to obtain better precision than the scheme without quantum correlation and it also prevents us from ambiguity in the frequency estimation procedure with GHZ correlations only. We show that the scheme can beat the shot-noise limit and, in addition, it is found that there is a trade-off relation between the precision of the frequency estimation and the decoherence rate in the atomic states.

arXiv:1501.00137Journal of Physics A Mathematical and TheoreticalDec 30, 20142 citations

Quantum Decoherence Measurements Through Two-Atom Correlations

L. Davidovich, M. Brune, J. M. Raimond +1 more

Springer eBooksJan 1, 19960 citations

Decoherence-enhanced measurements

Daniel Braun, John Martin

Quantum-enhanced measurements use highly non-classical quantum states in order to enhance the precision of the measurement of classical quantities, like the length of an optical cavity. The major goal is to beat the standard quantum limit (SQL), i.e. a precision of order $1/\sqrt{N}$ , where $N$ is the number of quantum resources (e.g. the number of photons or atoms used), and to achieve a scaling $1/N$ , known as the Heisenberg limit. Doing so would have tremendous impact in many areas, but so far only three experiments have demonstrated a slight improvement over the SQL. The required quantum states are generally difficult to produce, and very prone to decoherence. Here we show that decoherence itself may be used as an extremely sensitive probe of system properties. This should allow for a new measurement principle with the potential to achieve the Heisenberg limit without the need to produce highly entangled states.Quantum-enhanced measurements use highly non-classical quantum states in order to enhance the precision of the measurement of classical quantities, like the length of an optical cavity. The major goal is to beat the standard quantum limit (SQL), i.e. a precision of order $1/\sqrt{N}$, where $N$ is the number of quantum resources (e.g. the number of photons or atoms used), and to achieve a scaling $1/N$, known as the Heisenberg limit. Doing so would have tremendous impact in many areas, but so far only three experiments have demonstrated a slight improvement over the SQL. The required quantum states are generally difficult to produce, and very prone to decoherence. Here we show that decoherence itself may be used as an extremely sensitive probe of system properties. This should allow for a new measurement principle with the potential to achieve the Heisenberg limit without the need to produce highly entangled states.

arXiv:0902.1213Feb 7, 20093 citations

Precision measurements with a single quantum system

Klaus Mølmer, Alexander Holm Kiilerich, Pinja Haikka

Bulletin of the American Physical SocietyMar 5, 20150 citations

Correlation or decoherence? Quantum beats of atomic inversion in a resonant coherent field

N. K. Solovarov

It is shown that the standard reduction procedure (i.e., the calculation of the density matrix of the observable subsystem from the density matrix of a closed quantum system) bringing about decoherence corresponds to the limiting approximation, where the unobservable subsystem is assumed to be in the stationary state with minimum information (infinite temperature). An approximate set of interrelation (correlation) equations for the density matrices of the subsystems is derived. It is shown that the correlation of atom and field can be manifested as the inversion beats of a two-level atom in the known experimental scheme of resonator QED. Experimental observation of such beats would indicate that the observable subsystem (atom) generally conserves information about quantum coherence of the unobservable subsystem (field).It is shown that the standard reduction procedure (i.e., the calculation of the density matrix of the observable subsystem from the density matrix of a closed quantum system) bringing about decoherence corresponds to the limiting approximation, where the unobservable subsystem is assumed to be in the stationary state with minimum information (infinite temperature). An approximate set of interrelation (correlation) equations for the density matrices of the subsystems is derived. It is shown that the correlation of atom and field can be manifested as the inversion beats of a two-level atom in the known experimental scheme of resonator QED. Experimental observation of such beats would indicate that the observable subsystem (atom) generally conserves information about quantum coherence of the unobservable subsystem (field).

Journal of Experimental and Theoretical Physics LettersSep 1, 20031 citation

1/\sqrt{N}

, where

N

is the number of quantum resources (e.g. the number of photons or atoms used), and to achieve a scaling

1/N

, known as the Heisenberg limit. Doing so would have tremendous impact in many areas, but so far only three experiments have demonstrated a slight improvement over the SQL. The required quantum states are generally difficult to produce, and very prone to decoherence. Here we show that decoherence itself may be used as an extremely sensitive probe of system properties. This should allow for a new measurement principle with the potential to achieve the Heisenberg limit without the need to produce highly entangled states.