There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

This paper reviews recent experimental and theoretical progress concerning many-body phenomena in dilute, ultracold gases. It focuses on effects beyond standard weak-coupling descriptions, such as the Mott-Hubbard transition in optical lattices, strongly interacting gases in one and two dimensions, or lowest-Landau-level physics in quasi-two-dimensional gases in fast rotation. Strong correlations in fermionic gases are discussed in optical lattices or near-Feshbach resonances in the BCS-BEC crossover.

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Many-Body Physics with Ultracold Gases

Bose-Einstein condensation (BEC) has been observed in a dilute gas of sodium atoms. A Bose-Einstein condensate consists of a macroscopic population of the ground state of the system, and is a coherent state of matter. In an ideal gas, this phase transition is purely quantum-statistical. The study of BEC in weakly interacting systems which can be controlled and observed with precision holds the promise of revealing new macroscopic quantum phenomena that can be understood from first principles.

Bose-Einstein condensation in a gas of sodium atoms

비만아 부모의 돌봄 경험: q 방법론

We have observed Bose-Einstein condensation of pairs of fermionic atoms in an ultracold $^{6}\mathrm{Li}$ gas at magnetic fields above a Feshbach resonance, where no stable $^{6}\mathrm{Li}_{2}$ molecules would exist in vacuum. We accurately determined the position of the resonance to be $822\ifmmode\pm\else\textpm\fi{}3\text{ }\text{ }\mathrm{G}$. Molecular Bose-Einstein condensates were detected after a fast magnetic field ramp, which transferred pairs of atoms at close distances into bound molecules. Condensate fractions as high as 80% were obtained. The large condensate fractions are interpreted in terms of preexisting molecules which are quasistable even above the two-body Feshbach resonance due to the presence of the degenerate Fermi gas.

/pdf/condensation-of-pairs-of-fermionic-atoms-near-a-feshbach-4joqu9w4dc.pdf

Condensation of pairs of fermionic atoms near a Feshbach resonance.

We have observed Bose-Einstein condensation of pairs of fermionic atoms in an ultracold 6Li gas at magnetic fields above a Feshbach resonance, where no stable 6Li2 molecules would exist in vacuum. We accurately determined the position of the resonance to be 822+/-3 G. Molecular Bose-Einstein condensates were detected after a fast magnetic field ramp, which transferred pairs of atoms at close distances into bound molecules. Condensate fractions as high as 80% were obtained. The large condensate fractions are interpreted in terms of preexisting molecules which are quasistable even above the two-body Feshbach resonance due to the presence of the degenerate Fermi gas.

Condensation of Pairs of Fermionic Atoms Near a Feshbach Resonance

We have observed Bose-Einstein condensation of molecules. When a spin mixture of fermionic $^{6}\mathrm{L}\mathrm{i}$ atoms was evaporatively cooled in an optical dipole trap near a Feshbach resonance, the atomic gas was converted into $^{6}\mathrm{L}\mathrm{i}_{2}$ molecules. Below 600 nK, a Bose-Einstein condensate of up to 900 000 molecules was identified by the sudden onset of a bimodal density distribution. This condensate realizes the limit of tightly bound fermion pairs in the crossover between BCS superfluidity and Bose-Einstein condensation.

Observation of Bose-Einstein Condensation of Molecules

Observation of Bose-Einstein condensation of molecules.

We have produced a macroscopic quantum system in which a 6Li Fermi sea coexists with a large and stable 23Na Bose-Einstein condensate. This was accomplished using interspecies sympathetic cooling of fermionic 6Li in a thermal bath of bosonic 23Na. The system features rapid thermalization and long lifetimes.

/pdf/two-species-mixture-of-quantum-degenerate-bose-and-fermi-9zjbne9xl1.pdf

Claudiu A. Stan

Papers

Condensation of pairs of fermionic atoms near a Feshbach resonance.

Condensation of Pairs of Fermionic Atoms Near a Feshbach Resonance

Observation of Bose-Einstein Condensation of Molecules

Observation of Bose-Einstein condensation of molecules.

Two-species mixture of quantum degenerate Bose and Fermi gases.