The branching fractions from the excited state 6P[/2 of singly charged barium ion has been measured with a precision 0.03% in an ion trap experiment. This measurement along with the known value of the upper state lifetime allowed the determination of the dipole matrix elements for the transitions P-S and P-D to below the 1% level. Therefore, it is now possible to compare the many-body calculations of these matrix elements at a level which is of significance to any parity-nonconservation experiment on barium ion. Moreover, these dipole matrix elements are the most significant contributors to the parity-violating matrix element between the S-D transition, contributing up to 90% to the total. Our results on the dipole matrix elements are 3.305 ± 0.014 a.u. and 3.042 ± 0.016 a.u. for the S-P and P-D transitions, respectively. Trapping and laser cooling of ions provide a perturbationfree environment to measure atomic state lifetime [1], light shift [2], branching ratio [3], and other fundamental properties of atoms with high precision [4], This leads to the use of trapped and laser cooled ions for quantum state manipulation [5,6], atomic clocks [7] and to study fundamental interac tions [8], The study of fundamental interactions via atomic properties include measurements of the Lamb shift [9], the parity-nonconservation (PNC) in atomic system [10], the conserved vector current hypothesis [ 11 ], the electron-electric dipole moment (e-EDM) [12], etc. As most of the original experiments have been carried out with atomic beams, they suffered from large systematic uncertainties due to limited control over the environment. These systematics are largely absent for stored atomic systems, and in addition, they provide long observation time. Therefore, in recent years, trapped and laser cooled ions have emerged as potential candidates to per form high precision experiments of fundamental importance like atomic parity violation [13,14] and e-EDM [8], Barium ion is particularly suitable for the investigation of PNC as was pointed out by Fortson [13] because of its large nuclear charge and ease of laser cooling and trapping.The best atomic PNC measurement performed so far is that of cesium with a precision of 0.3% [10]. However, the nuclear anapole moment obtained from this measurement shows a discrepancy with other nuclear data strongly suggesting the need to measure atomic PNC in other species in order to verify or to go beyond the standard model of particle physics. In this context, a number of experimental groups are pursuing an ion-trap-based atomic PNC experiment which has been proposed to be capable of limiting systematic uncertainty to below the 1% level. In addition to the experiment, one also needs the theoretical value of the parity-violating dipole matrix element with a similar precision. In principle, different variants ol the coupled cluster theory [15][16][17][18] are capable of providing such precision, provided the many-body wave functions are accurately known. Precision measurement of atomic properties of the lo...

A new protocol for measuring the branching fraction of hydrogenic atoms with only statistically limited uncertainty is proposed and demonstrated for the decay of the P3/2 level of the barium ion, with precision below 0.5%. Heavy hydrogenic atoms like the barium ion are test beds for fundamental physics such as atomic parity violation and they also hold the key to understanding nucleo-synthesis in stars. To draw definitive conclusion about possible physics beyond the standard model by measuring atomic parity violation in the barium ion it is necessary to measure the dipole transition probabilities of low-lying excited states with a precision better than 1%. Furthermore, enhancing our understanding of the barium puzzle in barium stars requires branching fraction data for proper modelling of nucleo-synthesis. Our measurements are the first to provide a direct test of quantum many-body calculations on the barium ion with a precision below one percent and more importantly with no known systematic uncertainties. The unique measurement protocol proposed here can be easily extended to any decay with more than two channels and hence paves the way for measuring the branching fractions of other hydrogenic atoms with no significant systematic uncertainties.

We demonstrate an optical single qubit based on 6S 1/2 to 5D 5/2 quadrupole transition of a single Ba + ion operated by diode based lasers only. The resonance wavelength of the 6S 1/2 to 5D 5/2 quadrupole transition is about 1762 nm which suitably falls close to the U-band of the telecommunication wavelength. Thus this qubit is a naturally attractive choice towards implementation of quantum repeater or quantum networks using existing telecommunication networks. We observe continuous bit-flip oscillations at a rate of about 250 kHz which is fast enough for the qubit operation as compared to the measured coherence time of over 3 ms. We also present a technique to quantify the bit-flip error in each qubit NOT gate operation.

Precision atomic spectroscopy is presently the work horse in quantum information technology, metrology, trace analysis and even for fundamental tests in physics. Stable lasers are inherent part of precision spectroscopy which in turn requires absolute wavelength markers suitably placed corresponding to the atomic species being probed. Here we present, new lines of tellurium (Te2) which allows locking of external cavity diode laser (ECDL) for precision spectroscopy of singly charged barium ions. In addition, we have developed an ECDL with over 100 GHz mod-hop-free tuning range using commercially available diode from Nichia. These two developments allow nearly drift-free operation of a barium ion trap set-up with one single reference cell thereby reducing the complexity of the experiment.