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1、单原子量子态的制备1, 原子量子态的制备2, 原子辐射荧光的方向和强度3, 原子量子态的相干性1. 原子量子态的制备1, 2004 A neutral atom quantum register 1.51,5 State preparation and detectionFor qUimLiiiii Inibnnutiuij processing QIP) with atoiiiic pailiclcs. long living intcniiJ atomic atatcs serve as qubit states in which thn quantum mfoTmarion is enc
2、oded, Thpro fare?, cfficiont preparfiti and detect ion of states fitc basic requirements for any QIP schemes.The hyperfine ground states of cesium atoms am snitahle candida-tcjs fnr qubit states. Tn order tn tune the iLesonance frequency of the qnhit transition via. a mngriptic fiphl we choose the o
3、utermost Zeeman levpls as qubit states (see Figure 1.15) which are denoted in the followiiig as | 0) = | F = 4? mF = 4 and 11) = | F = 3： mj? = 3 J. The quiiutiaation ax澜 商 oridit.cd loiig the dipole trap.Figure i-15: Zeenian splitting of the cesium groiuid state. By optically pumping the atom to th
4、e stretehod Zeeman level F = 4、ef = A we can )eribTin al coher?Qt peialioiis on (lie effective twu-evel system denoted by 10) and | 1).1.5.1 State pipiiraticm by optical piitiipinxOptical iuiijpLii lawerIn all following cxpcriiuciits we iiklialic the trapped atcius iu state 10 prior to any further n
5、ianipulatiDn of the internal states. For this purpose we optically pump the atoms into state | 0 ? using a 0O leo) -O 1)b igure 2.6: Spontaneous emission of a photon. At time t = 0 the atom is in the excited 此时 |疚一 After HpoiitaoeQiiH mniion the at.(Jiu to the ground state |g. 1)： and the electromag
6、netic field mode is Dccupictl with one photon.The Hamiltonian of an atom interacting with a radiation field can be described by a Hamiltonian separated into three partsH = Ha 4- Hr + Hed(A. 16)where are Hr the Hamiltonian of a two level atoin and the raliation field, respectively, and are given as(A
7、.17)Hr(A.18)with the atomic states 砂 and the radiative field creation and annihilation operators 太 and &入,k The Hamiltonian for the interaction of the radiative field and the atom is切=(U) d = sE E如k如f”(标厂岫-诳置)10 01 (A.19) 人,k ijwith the coupling coefficient.。小 k =山源Ak E A IJ) -(A.20)Ve can rearrange the terms of eq. A.19 such that 巧 A 站 Vj z and knowing that the dipole matrix elements (i d i) vanish because of the fact that cl has odd parity. We get:Hed = (ggW D10 c/i)(
