Nature Physics 11, 389–392 (2015) doi:10.1038/nphys3280, http://arxiv.org/abs/1411.6289
Science 342, 1349 (2013)
All optical detectors to date annihilate photons upon detection, thus excluding repeated measurements. Here, we demonstrate a robust photon detection scheme that does not rely on absorption. Instead, an incoming photon is reflected from an optical resonator containing a single atom prepared in a superposition of two states. The reflection toggles the superposition phase, which is then measured to trace the photon. Characterizing the device with faint laser pulses, a single-photon detection efficiency of 74% and a survival probability of 66% are achieved.
American Control Conference (ACC), 2012
ISSN : 0743-1619
E-ISBN : 978-1-4673-2102-0
Print ISBN: 978-1-4577-1095-7
INSPEC Accession Number: 13036409
This work considers the theory underlying a discrete-time quantum filter recently used in a quantum feedback experiment. It proves that this filter taking into account decoherence and measurement errors is optimal and stable.
URL: http://link.aps.org/doi/10.1103/PhysRevA.87.042320
DOI: 10.1103/PhysRevA.87.042320
PACS: 03.67.Pp, 42.50.Pq, 42.50.Dv
The ubiquitous decoherence phenomenon is responsible for the lack of quantum superpositions at the macroscopic scale. It is increasingly difficult to isolate a quantum system from its environment when its size increases. Making use of the weird quantum properties of mesoscopic quantum states thus requires efficient means to combat decoherence. One option is real-time quantum feedback.
C Sayrin et al 2012 New J. Phys. 14 115007
doi:10.1088/1367-2630/14/11/115007
We present a method for reconstructing the average evolution of the photon number distribution of a field decaying in a high-Qcavity.
URL: http://link.aps.org/doi/10.1103/PhysRevLett.108.243602
DOI: 10.1103/PhysRevLett.108.243602
PACS: 42.50.Pq, 03.67.Pp, 42.50.Dv
Fock states with photon numbers n up
PHYSICAL REVIEW LETTERS Volume: 106 Issue: 15 Article Number: 157601 DOI: 10.1103/PhysRevLett.106.157601
The nitrogen-vacancy (NV) center in diamond is supposed to be a building block for quantum computing and nanometer-scale metrology at ambient conditions. Therefore, precise knowledge of its quantum states is crucial. Here, we experimentally show that under usual operating conditions the NV exists in an equilibrium of two charge states [70% in the expected negative (NV-) and 30% in the neutral one (NV0)].
Science 329 no. 5991 pp. 542-544
Projective measurement of single electron and nuclear spins has evolved from a gedanken experiment to a problem relevant for applications in atomic-scale technologies like quantum computing. Although several approaches allow for detection of a spin of single atoms and molecules, multiple repetitions of the experiment that are usually required for achieving a detectable signal obscure the intrinsic quantum nature of the spin’s behavior.