Quantum phase estimation with squeezed quasi-Bell states

In this paper we analyze the quantum phase estimation problem using continuous-variable, entangled squeezed coherent states (quasi-Bell states). We calculate the quantum Fisher information having the quasi-Bell states as probe states and find that both squeezing and entanglement might bring advantages, increasing the precision of the phase estimation compared to protocols which employ other continuous variable states, e.g., coherent or non-entangled states. We also study the influence of a linear (unitary) perturbation during the phase estimation process, and conclude that entanglement is a useful resource in this case as well.

[1]  M. Paris.  Quantum estimation for quantum technology , 2008, 0804.2981.

[2]  William J Munro,et al.  Quantum metrology with entangled coherent states. , 2011, Physical review letters.

[3]  Osamu Hirota,et al.  Entangled Nonorthogonal States and Their Decoherence Properties , 2001 .

[4]  Holland,et al.  Interferometric detection of optical phase shifts at the Heisenberg limit. , 1993, Physical review letters.

[5]  V. Giovannetti,et al.  Quantum parameter estimation affected by unitary disturbance , 2013, 1305.3069.

[6]  C. Helstrom.  Quantum detection and estimation theory , 1969 .

[7]  Augusto Smerzi,et al.  Optimal measurements in phase estimation: simple examples , 2013, Quantum Inf. Process..

[8]  Keiji Sasaki,et al.  Beating the Standard Quantum Limit with Four-Entangled Photons , 2007, Science.

[9]  S. Lloyd,et al.  Quantum-Enhanced Measurements: Beating the Standard Quantum Limit , 2004, Science.

[10]  S. Lloyd,et al.  Quantum metrology. , 2005, Physical review letters.

[11]  Alex Monras.  Optimal phase measurements with pure Gaussian states , 2006 .

[12]  Shuntaro Takeda,et al.  Quantum-Enhanced Optical-Phase Tracking , 2012, Science.

[13]  Christopher C. Gerry,et al.  Heisenberg-limit interferometry with four-wave mixers operating in a nonlinear regime , 2000 .

[14]  Entangled state based on nonorthogonal state , 2001, quant-ph/0101018.

[15]  C. Gerry,et al.  Nonlinear interferometer as a resource for maximally entangled photonic states: Application to interferometry , 2002 .

[16]  S. Lloyd,et al.  Advances in quantum metrology , 2011, 1102.2318.

[17]  Kae Nemoto,et al.  Quantum metrology for nonlinear phase shifts with entangled coherent states , 2012, 1203.2099.

[18]  J. Cirac,et al.  Improvement of frequency standards with quantum entanglement , 1997, quant-ph/9707014.