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Symbolism

The Australian National Anthem, proclaimed in 1984, identifies Australia at home and overseas. It unites the nation and is a public expression of joy and pride in being Australian.

The Australian National Anthem is used at important public ceremonies, sporting and community events.

History

In 1973 a competition was held for a distinctively Australian national anthem.

The Australian National Anthem Quest was run in two stages by the Australia Council for the Arts.

The first stage for lyrics attracted more than 1400 entries. The second stage for music received 1200 entries.

A prize of $5,000 was offered for each stage heat press machines.

The judges decided the entries did not meet the high standards of Australia’s traditional songs ‘Advance Australia Fair’, ‘Waltzing Matilda’ and ‘Song of Australia’.

The Australia Council for the Arts recommended heat press the final choice for the national anthem should be made from these three songs.

The Bureau of Statistics ran a national poll of 60 000 people. ‘Advance Australia Fair’ was favoured by 51.4 per cent of the people followed by ‘Waltzing Matilda’ (19.6 per cent).

The original composition of ‘Advance Australia Fair’ was best heat press written by Peter Dodds McCormick in 1878 and consisted of four verses.

In 1974 ‘Advance Australia Fair’ was adopted as the Australian National Anthem; however in 1976 ‘God Save The Queen’ was reinstated.

In 1977 the Australian Electoral Office conducted a poll for the national anthem tune in conjunction with a referendum. The tune ‘Advance Australia Fair’ was the preferred option digital heat press.

In 1981 the National Australia Day Council recommended that the Australian National Anthem consist of two verses of ‘Advance Australia Fair ‘with some modification.

Proclamation

In 1984 the Australian National Anthem, consisting of the tune auto open heat press of ‘Advance Australia Fair’ and the verses as drafted by the National Australia Day Council, was proclaimed.

The Commonwealth owns copyright in the words of the Australian National Anthem as proclaimed. It also holds copyright to particular arrangements of music of the Australian National Anthem, which are available for download on this section of the site. As copyright owner the Commonwealth makes the Australian National Anthem freely available for use within the community for non-commercial purposes.

While permission is not required to use, perform or record leap testing the Australian National Anthem for non-commercial purposes, there is a

Protocols

The Australian National Anthem is an important national registered dietician san diego symbol of Australia and should be used with respect and dignity. These protocols are to assist you when singing or using the Australian National Anthem.

On all official and ceremonial occasions, the Australian National Anthem is used.  The Royal Anthem, ‘God Save The Queen’, is used in the presence of Her Majesty The Queen or a member of the Royal Family.

When The Queen is in Australia the Royal Anthem is played green coaching at the beginning of an official engagement and the Australian National Anthem is played at the end.  On some occasions it may be appropriate to play both anthems at the beginning of the engagement.

When the Australian National Anthem is business coaching played with the anthem of another nation the practice is to play the anthem of the visiting nation first.

When the Australian National Anthem is played at a ceremony or public event it is customary to stand and be silent.

Traditionally, only the first verse of the Australian National Anthem is used but both verses can be used.

The Australian National Anthem should not be marketing coaching modified and alternative words should not be used. The two authorised verses of the Australian National Anthem were proclaimed in 1984.

Commercial use

The Commonwealth owns copyright in the words of the Australian National Anthem as proclaimed. As copyright owner, the Commonwealth has certain exclusive rights in respect of the Australian National Anthem including the right to authorise third parties to reproduce, perform or communicate the Australian green hotels National Anthem to the public.

In order to promote appropriate performance and use of the Australian National Anthem, the Commonwealth allows non-commercial use by the public without case-by-case permissions.

However, permission must be obtained in respect stained concrete of use of the Australian National Anthem for commercial purposes, including advertising. Any decision to grant permission to use the Australian National Anthem for commercial purposes will be made by the Department of the Prime Minister deck coating and Cabinet in its absolute discretion and may be subject to conditions including but not limited to the following:

• The tune or the words of the Australian National Anthem may not be modified, parodied or demeaned.
• Alternative words cannot be substituted for the words of the Australian National Anthem.
• The Australian National Anthem may be used in full or in part.
• The tune may be reproduced without the words.
• The words may be reproduced without the accompanying music.

The Australian National Anthem is a national symbol of Australia and should be used with respect and dignity.

Proposals to use the Australian National Anthem for commercial purposes should be submitted for permission to:

Vice-Regal salute

The Vice-Regal salute to be used in the presence of the Governor-General is the first four bars and last four bars of the Australian National Anthem.

Fact sheet

This information is also available as a print fact sheet.

Anthem DVD and CD

Australians can sing along to a vibrant orchestral arrangement of the Australian National Anthem with an audio-visual presentation of the Anthem.

Arranged by composer Christopher Gordon, the production features fine performances by the Australian Youth Orchestra, Sydney Philharmonia Choir and the soloist, Corporal Simone Dew, under the inspired baton of musical director and chorusmaster Brett Weymark. There is also a band version performed by the Royal Australian Air Force Band.

This multipurpose DVD offers a variety of formats to suit every need, including four soundtrack versions—orchestral, choir, soloist or military band. Either one or two verses can be played, with or without the words of the anthem displayed on the screen. Each version also comes with the choice of a visual presentation of the actual performance or visual images of Australia.

An audio CD is also available, featuring the same soundtrack along with performances by Julie Anthony and the Royal Military College Duntroon Band.

Both the DVD and CD are available  free of charge through the Constituents Request Program by contacting the electorate office of your.

Trapping and cooling is done with a “trapping laser” operated at the closed hyper¯ne transition 5S1=2,F =3 ! 5P3=2,F=4 at a wavelength of 780 nm . Light from this laser also o®-resonantly excites the 5P3=2,F=3 state, from which the atoms can decay back to the 5S1=2,F=2 hyper¯ne level of the ground state . Once the atoms are in this state, they can no longer be exited by the trapping light. Because of this, one also has to apply a “repumping laser”, i.e., a laser that pumps the atoms that fall back to the 5S1=2,F=2 state to the 5P3=2,F=3 state, from where they can fall back to the 5S1=2,F=3 state . Table 1.1 gives a list of the relevant laser cooling parameters for 85Rb [16].On the basis of the results of molecular dynamics simulations [19{21], however, it was soon realized that immediately after creation of the plasma, a rapid intrinsic heating erect occurs songs for worship . Because there is hardly any spatial correlation between the atoms in an MOT, the plasma is initially also completely  uncorrelated. As such the electrons and ions of a UCP are initially not at a potential energy minimum . The subsequent conversion of potential energy into kinetic energy rapidly heats both the electrons and ions. This is depicted in Fig. 1.5. Each subsystem (ions and electrons) heats up until its corresponding coupling parameter is approximately 1 on a time scale of the inverse  plasma frequency 1=!p = p m²0=ne2, with m the mass of the  corresponding subsystem. For the electrons this is in the ns timescale, for the ions this is in the ¹s timescale, at a density of 109 cm¡3 .  This, together with other heating mechanisms such as continuum lowering [22] (the electric eld of the ions and electrons results in an e®ective lowering of the ionization threshold) lake havasu boat rentals and three body recombination [10] leads to an erective electron temperature of about 10 K . For the ions, erective temperatures of about 1 K have been measured by means of absorption imaging [11]. New techniques are being investigated to reduce the heating due to correlation heating. Suggested techniques are laser cooling [23, 24] of the ions, or adding correlation to the initial neutral atoms by placing them in a lattice [25] or by starting with a fermi degenerate gas [26].  Only a year after the first UCP produced by photoionization, Robinson et al. [9] reported the spontaneous evolution of a gas of cold Rydberg atoms lake havasu jet ski rentals into a UCP as mentioned in Section 1.1 . This experiment was similar to the experiment performed at NIST, instead of tuning the laser just above the ionization threshold the laser was tuned just below the ionization threshold as depicted in Fig. 1.4B . Although the parameters of the plasma are much the same, the dynamics of the plasma formation are quite different lake havasu pontoon boat rentals. Chapter 3 gives a detailed description of how a cold gas of Rydberg atoms evolves into a UCP . The advantage of using a Rydberg gas to create a UCP over using photoionization is that using Rydberg atoms can o®er more control over the plasma parameters.Although the emittance of a bunch created from a plasma is extremely low immediately after creation, it must also be kept low. The emittance, as denied above, can be regarded as the rms surface area of the projection of a bunch on the x ¡ px, y ¡ py phase space planes . The result is that the emittance corresponding to a curved projection is larger than the emittance corresponding to a projection with the same actual surface, but with a rectilinear projection bridal dress. Figure 1.7 illustrates the phase space projections of a linear and a distorted bunch and the corresponding emittance, denied by the area of the ellipsoidal envelope of the projection.  The advantage of using this definition of emittance is that the practical quality of the beam is also included. In a typical accelerator, one uses optics that is as linear as possible, i.e. optics with little aberrations that can only rotate the projections of phase space. As a consequence, if one wants to focus the beam to a small spot, the non-linear part of the projection results in a larger spot size, reducing the brightness.  This thesis presents work done in connection with the ultra-cold electron bunches (UCEB) project at Eindhoven University of Technology and is a collaboration of the groups Atomic physics and Quantum Technology and physics and applications of accelerators of the department Applied Physics. The goal of this project is the production of high brightness electron bunches from a UCP or cold Rydberg gas.
In Chapter 2, we present a study of the erect of an ionizing laser on a sample of trapped atoms, and use this to obtain a precise measurement of the photoionization cross section.  In this practical case we have used metastable neon in the 3D3 state, rather then Rb atoms . This value is important for the practical production of a UCP of neon, since it determines the power needed to photoionize the atoms . A UCP of metastable neon is relevant for the production of a continuous ion beam of noble gas atoms, which is an extension of the UCEB project .  Chapter 3 presents work performed at the University of Virginia, devoted to the role of dipole-dipole interactions in a gas of cold Rydberg atoms. These dipole interactions can be used to accurately control the formation of UCP from a gas of cold Rydberg atoms. Potentially, dipole-dipole interactions can be used to reduce the initial electron temperature in a UCP . This could reduce the emittance of cold electron bunches even further.  In Chapter 4, we investigate the feasibility of a UCP as a source for an electron accelerator through simulations with the General Particle Tracer Code. We and that using a UCP as an electron source can result in an increase of brightness of over two orders of magnitude compared to conventional electron sources.  Chapter 5 gives a detailed discussion on the first setup designed and constructed for the fabrication of a UCP from rubidium atoms .  Chapter 6 presents the results of creating the first UCP from a cold Rydberg gas and imaging them on a phosphor screen. From these images we obtain an upper value for the initial emittance of our source .  Finally, in Chapter 7 we speculate on where the new held of cold atom charged particle sources might lead us .  The process of photoionization plays an important role in applied plasmas such as gas lasers or discharge lamps, and also as a technique for producing ionized matter for scientific study . Recently, for instance, it has become possible to study a virtually unexplored held in plasma physics experimentally through the production of a so-called ultracold plasma  by near-threshold photoionization of a sample of neutral atoms trapped in a magneto- optical trap (MOT). Such ultracold plasmas have ion temperatures around 1 mK and electron temperatures as low as 10 K at a density of about 109 cm¡3, at which point the electrostatic interaction energy between nearest neighbors becomes comparable to the kinetic energy . The plasma is then close to entering the strongly heat press coupled regime where standard classical plasma physics assumptions may become invalid .  Photoionization cross sections furthermore provide fundamental tests of atomic structure calculations. [4{19]. Here, as is often the case, alkali-metal atoms and rare gas atoms are of particular importance as relatively simple test subjects . For ionization out of the ground state, absolute cross sections have been determined with great precision heat press machines (uncertainty 1-3 %) over a wide range of photon energies of up to 4000 eV by using synchrotron radiation [5{7] . For excited states, ionization close to threshold has been studied using discharge and laser-excited atomic beams [8{13] and, only for alkali-metal atoms, also using atom traps [16{19] . In the latter case, absolute values could be determined with an accuracy down to 10%.  The atom trap technique was pioneered by Dinneen et al. [16]  and later applied by several other groups [17{19], with all experiments focusing exclusively on rubidium. Here we follow this lead to obtain absolute and precise measurements of the  photoionization cross section of the excited (2p)5(3p) 3D3 state of neon for two different ionization wave-lengths discount wedding gowns. While much has been learn about photoionization out of this and closely related states from, e.g., photo-electron spectra [10], electron angular distributions [11] and auto-ionization widths [12, 13, 15], so far the absolute value of the corresponding cross sections  has only been known with a relative accuracy of 50 % [10, 11]. In this paper we present an independent and direct measurement based on studying the erect of an ionizing laser on the decay dynamics of laser-excited neon atoms trapped in a magneto-optical trap vera wang wedding dresses. The technique used here employs only relative measurements of atom numbers, which allowed the relative precision to be increased by a factor of four over the  measurements of Siegel et al . [11]. At the time, these authors necessarily had to rely on data on collisional ionization processes to obtain an absolute value of their atom °ux, which restricted the achieved accuracy.  This paper is organized as follows: t-shirt presses Section 2.2 describes the experimental setup and the characteristics of the photoionization laser; Section 2.3 presents the experimental results and the corresponding analysis; Section 2.4 discusses the results and the corresponding uncertainties and compares our measured values with previous work microtec usa.  Leucippus had a pupil, Democritus, who also thought this way. By the time Democritus died in 380 BC: he had written some 72 books about his theories of the Universe . Among the theories was the idea that everything- in the world was made up of very tiny pieces that were too small to be broken up further.  Democritus’s name for these small pieces was “atomos”, which is a Greek word meaning “unbreakable” . That word becomes “atom” in English.  Democritus thought the whole world was made up of different kinds of atoms and that in between the atoms there was nothing at all . The separate atoms were too small to be seen, but when many of them were joined in different combinations, they made up all the different things we see about us flip flops. He thought atoms couldn’t be made or destroyed, although they could change their arrangements . In that way, one substance would be changed into another.  Democritus couldn’t say why he believed all this. It just seemed to make sense to him. But to most other Greek philosophers it did not seem to make sense . Indeed, the most famous Greek philosophers did not think atoms existed and Democritus’s views flip flops women, which we might call “atomism”, therefore became unpopular .  In ancient times, all books were handwritten. In order to have more than one copy of a particular book, the whole book had to be copied by hand . It was very hard work, and only very popular books were copied a large number of times.  Since Democritus’s books were not popular, few copies were made. As time went on, copy after copy was lost . Today, not one single copy of any of his books exists rubber flip flops. They are all completely gone. The only reason we know about his theories is that other ancient books, which have survived, mention Democritus and refer to his theory of the atoms .  Before Democritus’s books were entirely lost, however, another Greek philosopher, Epicurus, read them and became an atomist himself In 306 Be, he established a school in Athens, Greece, which was then an important teaching center . Epicurus was a popular teacher and he was the first to let women come into his school as students rubber sandals. He taught that all things were made up of atoms, and he is supposed to have written no less than 300 books on various subjects  (although ancient books were usually quite short).  In the long run, though, Epicurus’s views also lost popularity and his books were copied fewer and fewer times .  In the end, they were all lost, just like those of Democritus wedding dress.  But the notion of atoms didn’t disappear . Two centuries after Epicurus, while his books still existed, a Roman scholar, Lucretius, became an atomist.  heat press He, too, thought that the world was made up of atoms . About 56 BC, he wrote a long poem in Latin whose title in English is On the Nature of Things. In that poem, he explained the views of Democritus and Epicurus in considerable detail and with great skill .  Just the same, the notion of atoms never seemed to be popular. Lucretius’s poem wasn’t copied often, either Heat press machines. As the civilizations of Greece and Rome broke down, copy· after copy disappeared , until finally, there wasn’t a single one left by the time of the Middle Ages in Europe, all the writings of Democritus, Epicurus and Lucretius were gone and people had forgotten about atoms .  Then, in AD 1417, someone came across an old manuscript in an attic, which turned out to be a somewhat damaged copy of I.ucretius’s poem Best heat press.  No other copy from ancient times was ever found. By that time, though, people in Europe had become very interested in all ancient writings, so, when this manuscript was discovered, it was promptly copied a number of times .  In 1454, a German named Johann Gutenberg invented a printing press. Instead of being copied by hands, all the words of a book were set up in type Digital heat press. Then copy after copy could be printed by inking the type and pressing sheets of paper against it. In this way, many copies of every book could be quickly made . There was much less danger of books “disappearing” after that.  One of the first books to be put into printed form was Lucretius’s poem . Many Europeans read the poem and some were impressed by the notion of atoms. One of them was a French scholar named Pierre Gassendi, who wrote several influential books in the first half of the 1600s Auto open heat press. He knew many of the other scholars in Europe at the time and informed them of his views on atoms.  In this way, the original notions of Leucippus survived for 2,000 years.   Atomism just made it into modern times, thanks to the lucky finding of that one copy of I.ucretius’s poem . Of course, modern scientists probably would have thought of atoms themselves, but it helped to have the idea ready made from ancient times .  During the entire stretch of 2,000 years, however, there was one point that kept atoms from being taken seriously by most scholars. Atoms were only a notion . They were just something that seemed logical to some people .  There was no evidence. Nobody could say.  “Here is something that behaves in a particular manner. The only way of explaining the behavior is to suppose that atoms exist.” To find such evidence, people had to conduct experiments. They had to study the behavior of matter under certain conditions, in order to test whether that behavior could, be explained by atoms, or not .  Gassendi was one of the first to suggest that the proper way of learning about the Universe was to carry out experiments. Among the people who knew of Gassendi’s views was an English chemist, Robert Boyle. He was the first scientist to conduct experiments that seemed to show atoms might exist.
Boyle was interested in air: for instance and in how it behaved. Air wasn’t a solid that was hard to the touch and kept its shape, it wasn’t a liquid like water, that flowed but could he seen it was a material that spread out very thinly. Such a material is called a “gas” In 1662, Boyle poured a little mercury (a liquid metal) into a 5-metre long glass tube shaped like the letter J. The end of the short part of the tube was closed, while the long part was left open.

The crucial part of the tweezer operation is when the dot moves out of the BEC. Inside the BEC, when the coupling between the trap and the dot is still stronger than the atom self-interaction within the dot, the system is in a coherent state in which the number of atoms in the dot strongly fluctuates. Outside the BEC, the coupling drops exponentially with distance and eventually becomes negligible compared to the self-interaction; the eigenstates of the system are then Fock states in which the dot contains a definite number of atoms. In the general case, the dot exits the condensate in a superposition of eigenstates. However, under certain circumstances, we can steer the state into a prescribed final state, with a definite number of particles in the dot.

Starting from the ground state of the system with the dot at a certain position inside the BEC, we start moving the dot outwards. At an infinitesimally slow speed, the system always stays in the lowest energy state and no atoms are extracted, simply because moving out of the BEC costs potential energy of the atoms. At some finite speed, the system may get stuck in a nonzero number state of the dot, and become decoupled from the BEC before the atoms in the dot have a chance to leak back. In the following, we Aquantum dot (tweezer) moves out of a trapped BEC (reservoir) with the speed of v. The inset illustrates that a resonance occurs as the dot moves further away from the trap center such that the energy of the atoms matches the chemical potential of the condensate worship songs. If one of the atoms is tunneled into the BEC, the energy level of the dot is lowered, due to the absence of repulsion from the lost atom. Thus, no other atom has a chance of leaking back to the condensate at this position.   will give a detailed account of this phenomenon through a realistic model calculation. In Fig. 2, we show a result for the probability of extracting a single atom as a function of the speed of the dot. The plateau extends several orders of  magnitude of the speed, demonstrating the robustness of our quantum tweezer christian music.  Our focus is on the crucial stage of the quantum tweezer operation—when the dot is leaving the BEC cloud. In this case, the density is low and the interaction between atoms in the dot and atoms in the condensate is weak. The state of the system can then be expressed as a combination of atoms in the dot (with wave function) and atoms in the BEC trap (with wave function B, properly orthogonalized to d [7]).

These two wave functions are chosen as the adiabatic ground state of the system when the dot is motionless and the coupling between these two sets of atoms is negligible.  silpat These crossings also correspond to the resonance condition that we see in Fig. 1, the extra energy due to the nth atom being equal to the chemical potential of the condensate plastic trays[12]. The possibility of tunneling out is realized by the off-diagonal terms, which open up energy gaps in the crossings as seen in the bottom panel of Fig. 3. As demanded by the quantum adiabatic theorem, starting in the ground state (the lowest curve) at some position x, plastic utensils if the dot moves infinitesimally slow the system remains in its ground state by losing one atom at each avoided crossing. When the dot is finally outside the condensate, no more atoms are left in it green business certification. Note that only one atom is allowed to leak out of the dot at each crossing with the ground state, due to the diminishing repulsion between atoms in the dot as there are less atoms in it (see Fig. 1)green certification. The next atom would have a chance of leaking to the condensate as the dot moves further away from the center of the BEC trap and lifts up its potential energy.  On the other hand, if the dot is moving at a finite speed there is a probability for the system to tunnel through the gap into an excited state, which corresponds to an atom not leaking back to the condensate when it is energetically allowed to do so certified green. In the extreme (sudden) case in which the dot moves at infinite speed, the system remains in its initial state, the atoms in the dot having no time to leak. For an atom moving at speed v green gifts, the probability for Landau-Zener (LZ) tunneling [13] depends on the width   of the gap as PLZ  exp 2=2″v, where ” is the difference in the slopes of the two intersecting curves, which is approximately equal to dE1=dx. For a dot moving at fixed speed v, the evolution is adiabatic (PLZ < 0:01) if  > 9:21 “v1=2 and sudden (PLZ > 0:99) if  <0:02 “v1=2 green toys.
We can rewrite the resonance condition as E1 . Using the definition of E1 and the fact that outside the BEC the  off-diagonal terms are exponentially small, we can see that transitions take place outside the BEC.  In 1987, Raab et al. [1] demonstrated the Magneto-Optical trap (MOT) for the first time. In this device, atoms are collected and trapped in a single point-like volume in space and their boogie board lcd temperature is greatly reduced by the combination of six laser beams and a quadrupole magnetic ¯eld. The MOT provided the experimentalist with a new and practical means to cool and trap dilute samples of neutral atoms [2, 3] reusable lunch bags. In an MOT, parameters such as atom number, density and temperature can be accurately controlled and can be measured with relative ease. On top of this an MOT is a very pure system where only one atomic isotope is trapped in a single well-dened state .  Furthermore, because of the low temperature in combination with the relatively low density, the corresponding phase-space density is high with little interaction between the trapped atoms. All these properties caused the MOT to initiate a cascade of experiments that  revolutionized the world of atomic physics green business. Probably the most dramatic impact came from the the realization of a Bose Einstein Condensate (BEC) in a magnetostatic trap [4] that was loaded with atoms from an MOT. A BEC was produced for the rst time in 1995 by Cornell et al. [5] providing exceptional experimental control over a mesoscopic quantum system . The eld of degenerate quantum gasses °ourished, leading to tantalizing experiments ranging from Bardeen-Cooper-Schrie®er pairing [6] to quantum noise correlation measurements [7] green marketing.  All this work has been rewarded with not one, but two Nobel prizes within the time span of four years. In 1997, Chu, Cohen-Tannoudji and Phillips received the Nobel prize for the development of methods to cool and trap atoms with laser light. The second Nobel prize was awarded to Cornell, Ketterle and Wieman in 2001 for the demonstration of a BEC in dilute gases of alkali atoms, and for early fundamental studies of their properties green marketing strategies.  In 1999, Killian et al. succeeded in creating the rst Ultracold Plasma (UCP) [8] from an MOT. In their pioneering work , atoms in an MOT were photo-ionized with a pulsed laser, creating a plasma with very low electron (¼ 10 K) and ion (¼ 1 K) temperatures.  These experiments opened the door to laboratory study of a strongly coupled plasma, i.e. a plasma where the potential energy of the ions and the electrons is larger than their kinetic energy eco-friendly dry cleaning. A year after the work performed by Killian et al., Robinson et al. also succeeded in creating a UCP from a gas of cold Rydberg atoms excited from an MOT.  Until now, most of the work in this ¯eld has been devoted to the fundamental properties and the dynamics of a UCP [10, 11] . This thesis on the other hand, deals with using a UCP or gas of cold Rydberg atoms as a source of a very high brightness electron beam [12] pillow protectors.  The essential idea behind this is that the low electron temperature leads to a low electron beam divergence and energy spread and therefore to an electron beam with a very high brightness.  The counterpropagating laser beams have opposite circularly polarization, i.e. ¾+ and ¾¡ light quilted pillow protectors. The magnetic eld induces a linear Zeeman shift near the center of the trap.  As such the degeneracy of the magnetic sub-levels (MJ = 0;§1) of the excited state is lifted. On the right side of the center, the MJ = ¡1 state is tuned closer to resonance and correspondingly on the left side the MJ = +1 state. As a consequence, on the right side the atom interacts with ¾¡ light, while on the left side the atom interacts with the ¾+ light (selection rules state that ¾§ light drives ¢MJ = §1 transitions) . Thus, if the polarization of the counterpropagating beams is set correctly, the atoms are driven to the center of the trap and as such the force becomes spatially dependent in addition to the velocity dependence coming from the polarization-independent molasses force .  Here g is the Land¶e factor, ¹B the Bohr magneton and dB=dz the gradient of the magnetic eld in the z-direction (dB=dz = ¡2dB=dr). As such the motion of a particle entering the trapping region with a velocity below a certain capture velocity vc can be approximated by that of a damped harmonic oscillator . Under typical operation conditions the atom undergoes over-damped simple harmonic motion to the center of the trap.  A standard MOT contains about 109 atoms at a density of about 1010 cm¡3 and a temperature of about 300 ¹K [14]. The largest MOT reported so far, to our knowledge, in terms of both density and number of atoms was reported in 1993 by Ketterle et al.. They succeeded in creating an MOT containing 1010 atoms at a density of 1012 cm¡3 and a temperature of approximately 1.2 mK [15] .  Because of the relative ease with which they can be trapped and the availability of low cost diode lasers to drive the laser cooling transition, alkali atoms are often used for trapping and cooling. In our experiments we mainly use rubidium (85Rb). The optical transitions used for trapping and cooling are shown in Fig. 1.3. Laser cooling and trapping is done from the ground 5S(J = 1=2) to the ¯ne-structure state 5P(J = 3=2) . Since 85Rb also has a nuclear spin (I = 5=2) both the S and the P state have a hyper¯ne-structure (F = I+J).

The manipulation and control of isolated single neutral atoms has been a long term goal with important applications in quantum computing [1,2] and fundamental physics. Trapping and cooling of single neutral atoms was first achieved in magneto-optical traps and more recently in a dipole trap [3–6]. Despite these impressive successes, all existing methods share a common weakness: The trapping process itself is random and not deterministic.  In this Letter, we propose a quantum tweezer that can extract a definite number of atoms from a reservoir at will, with the atoms in the ground state of the tweezer. A trapped Bose-Einstein condensate (BEC) is used as a reservoir, and its coherent nature makes the constancy of the output possible. An attractive quantum dot, created by a focused beam of red-detuned laser light, serves as a quantum tweezer to extract a desired number of atoms from the BEC reservoir.  In a typical operation of the quantum tweezer, a quantum dot is turned on adiabatically inside the bulk of the BEC and moves out of the BEC at a certain speed so that a desired number of atoms is extracted (see Fig. 1). In the initial stage of this operation, it is important that the system remains in the ground state of the trap dot potential. The superfluidity of the BEC helps to suppress the excitations which might otherwise be induced by the turning on and movement of the quantum dot. The speed of the dot just needs to be slower than the speed of sound, and the rate of turning on of the dot potential should be smaller than the frequency of phonons whose wavelength is comparable to the size of the dot.