arXiv subjects

B. Qi

Publications and source records attributed to B. Qi.

28 records · Page 2Linked to original sources

arXiv2011

The first candidate for chiral nuclei in the $A\sim80$ mass region: $^{80}$Br

Excited states of $^{80}$Br have been investigated via the $^{76}$Ge($^{11}$B, $α$3n) and $^{76}$Ge($^{7}$Li, 3n) reactions and a new $ΔI$ = 1 band has been identified which resides $\sim$ 400 keV above the yrast band. Based on the experimental results and their comparison with the triaxial particle rotor model calculated ones, a chiral character of the two bands within the $πg_{9/2}\otimes νg_{9/2}$ configuration is proposed, which provides the first evidence for chirality in the $A\sim80$ region.

nucl-ex↗

arXiv2011

Chirality in odd-$A$ Rh isotopes within triaxial particle rotor model

Adopting the fully quantal triaxial particle rotor model, the candidate chiral doublet bands in odd-$A$ nuclei $^{103}$Rh and $^{105}$Rh with $πg_{9/2}^{-1}\otimesνh^{2}_{11/2}$ configuration are studied. For the doublet bands in both nuclei, agreement is excellent for the observed energies over entire spin range and $B(M1)/B(E2)$ at higher spin range. The evolution of the chiral geometry with angular momentum is discussed in detail by the angular momentum components and their probability distributions. Chirality is found to change from chiral vibration to nearly static chirality at spin $I=37/2$ and back to another type of chiral vibration at higher spin. The influence of the triaxial deformation $γ$ is also studied.

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arXiv2010

Chiral geometry of higher excited bands in triaxial nuclei with particle-hole configuration

The lowest six rotational bands have been studied in the particle-rotor model with the particle-hole configuration $πh^1_{11/2}\otimesνh^{-1}_{11/2}$ and different triaxiality parameter $γ$. Both constant and spin-dependent variable moments of inertial (CMI and VMI) are introduced. The energy spectra, electromagnetic transition probabilities, angular momentum components and $K$-distribution have been examined. It is shown that, besides the band 1 and band 2, the predicted band 3 and band 4 in the calculations of both CMI and VMI for atomic nuclei with $γ=30^\circ$ could be interpreted as chiral doublet bands.

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arXiv2009

Candidate MKiD nucleus 106Rh in triaxial relativistic mean-field approach with time-odd fields

The configuration-fixed constrained triaxial relativistic mean-field approach is extended by including time-odd fields and applied to study the candidate multiple chiral doublets (MKiD) nucleus 106Rh. The energy contribution from time-odd fields and microscopical evaluation of center-of-mass correction as well as the modification of triaxial deformation parameters beta, gamma due to the time-odd fields are investigated. The contributions of the time-odd fields to the total energy are 0.1-0.3 MeV and they modify slightly the gamma values. However, the previously predicted multiple chiral doublets still exist.

nucl-th↗

arXiv2008

Chirality in odd-$A$ nucleus $^{135}$Nd in particle rotor model

A particle rotor model is developed which couples several valence protons and neutrons to a rigid triaxial rotor core. It is applied to investigating the chirality in odd-$A$ nucleus $^{135}$Nd with $πh_{11/2}^2\otimesνh^{-1}_{11/2}$ configuration for the first time in a fully quantal approach. For the two chiral sister bands, the observed energies and the $B(M1)$ and $B(E2)$ values for the in-band as well as interband transitions are reproduced excellently. Root mean square values of the angular momentum components and their probability distributions are used for discussing in detail the chiral geometry of the aplanar rotation and its evolution with angular momentum. Chirality is found to change from a soft chiral vibration to nearly static chirality at spin $I=39/2$ and back to another type of chiral vibration at higher spin.

nucl-th↗

arXiv2008

Signature splitting in $^{173}$W with triaxial particle rotor model

A particle rotor model with a quasi-neutron coupled with a triaxially deformed rotor is applied to study signature splitting for bands with intruder orbital $\nu7/2^{+} [633]$ and non-intruder orbital $\nu5/2^{-}[512]$ in $^{173}$W. Excellent agreement with the observed energy spectra has been achieved for both bands. Signature splitting for band $\nu7/2^{+} [633]$, and band $\nu5/2^{-}[512]$ before the onset of signature inversion, is satisfactorily reproduced by introducing the $γ$ degree of freedom. The phase and amplitude of signature splitting in band $\nu5/2^{-}[512]$ is attributed to strong competition between $2f_{7/2}$ and $1h_{9/2}$ components. However, the explanation of signature inversion in band $\nu5/2^{-}[512]$ self-consistently is beyond the present one quasi-neutron coupled with a triaxially deformed rotor.

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arXiv2007

Chiral bands for quasi-proton and quasi-neutron coupling with a triaxial rotor

A particle rotor model (PRM) with a quasi-proton and a quasi-neutron coupled with a triaxial rotor is developed and applied to study chiral doublet bands with configurations of a $h_{11/2}$ proton and a $h_{11/2}$ quasi-neutron. With pairing treated by the BCS approximation, the present quasi-particle PRM is aimed at simulating one proton and many neutron holes coupled with a triaxial rotor. After a detailed analysis of the angular momentum orientations, energy separation between the partner bands, and behavior of electromagnetic transitions, for the first time we find aplanar rotation or equivalently chiral geometry beyond the usual one proton and one neutron hole coupled with a triaxial rotor.

nucl-th↗

arXiv2007

Examining the chiral geometry in 104Rh and 106Rh

The criteria for chiral doublet bands based on one particle and one hole coupled to a triaxial rotor have been summarized. Two representative cases in $A\sim100$ odd-odd nuclei, nearly degenerate $ΔI =1$ doublet bands in $^{104}$Rh and $^{106}$Rh are checked against these chiral criteria. It is shown that $^{106}$Rh possesses better chiral geometry than $^{104}$Rh, although the energy near degeneracy is achieved in $^{104}$Rh in comparison with the constant energy separation of doublet bands in $^{106}$Rh.

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arXiv2007

Doublet bands in $^{126}$Cs in the triaxial rotor model coupled with two quasiparticles

The positive parity doublet bands based on the $πh_{11/2}\otimesνh_{11/2}$ configuration in $^{126}$Cs have been investigated in the two quasi-particles coupled with a triaxial rotor model. The energy spectra $E(I)$, energy staggering parameter $S(I)=[E(I)-E(I-1)]/2I$, $B(M1)$ and $B(E2)$ values, intraband $B(M1)/B(E2)$ ratios, $B(M1)_{\textrm{in}}/B(M1)_{\textrm{out}}$ ratios, and orientation of the angular momentum for the rotor as well as the valence proton and neutron are calculated. After including the pairing correlation, good agreement has been obtained between the calculated results and the data available, which supports the interpretation of this positive parity doublet bands as chiral bands.

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arXiv2005

Practical Decoy State for Quantum Key Distribution

Decoy states have recently been proposed as a useful method for substantially improving the performance of quantum key distribution. Here, we present a general theory of the decoy state protocol based on only two decoy states and one signal state. We perform optimization on the choice of intensities of the two decoy states and the signal state. Our result shows that a decoy state protocol with only two types of decoy states--the vacuum and a weak decoy state--asymptotically approaches the theoretical limit of the most general type of decoy state protocols (with an infinite number of decoy states). We also present a one-decoy-state protocol. Moreover, we provide estimations on the effects of statistical fluctuations and suggest that, even for long distance (larger than 100km) QKD, our two-decoy-state protocol can be implemented with only a few hours of experimental data. In conclusion, decoy state quantum key distribution is highly practical.

quant-ph↗