Quadron-polariton: a new semiconductor quasiparticle

真实粒子的基本性质（质量、电荷、自旋）是稳定的，而且可以永远确定，与之相反，准粒子在晶体中传播的性质可以通过晶体结构的适当设计和不同的外部因素（加热、光照射晶体、电场或磁场的应用）来调节。这样就可以用相对简单的方法创造出新的准粒子。这个项目提出了一种新的准粒子，以前从未被观察到，也没有在理论上描述过。我们称之为四极子。四分子，因为它是由四个基本准粒子（三个电子和一个空穴）和极化子组成的，因为它是由光将其极化传递给晶体而产生的。人们期望四极子具有真正非凡的性质。它们带一个负电荷，等于两个电子电荷。它们的有效质量大约是自由电子质量的1万倍。它们在空间上延伸到几个波长的光上。最后，它们具有整数自旋，因此服从玻色-爱因斯坦统计。这就是为什么，我们期望四极子能够形成超流体，也就是说，粗略地说，统一它们的能量和速度。理论上，由于四极化子的质量很轻，在特殊设计的晶体结构中，即使在室温下，它们的凝结也可能发生。四极子的超流体是带电的，这就是为什么我们期望它的产生会导致超导现象（没有任何施加电压的电流循环）。观察到光诱导的超导性将是一个非凡的发现，而且具有相当大的经济效应。我们将通过对超薄人工晶体结构中的四极化子进行复杂的理论和实验研究，为这一观察铺平道路。

Contrary to real particles whose basic properties (mass, charge, spin) are stable and may be determined once and forever, the properties of quasiparticles propagating in crystals can be tuned by a proper design of crystal structures and different external factors (heating, illumination of the crystal by light, application of electric or magnetic fields). This allows for creation of new kinds of quasiparticles by relatively simple means. This project proposes a new quasiparticle which has never been observed nor theoretically described before. We call it quadron-polariton. Quadron because it is composed by four elementary quasiparticles (three electrons and one hole) and polariton because it is created by light passing its polarization to the crystal. The quadron-polaritons are expected to have truly remarkable properties. They carry a negative charge equal to two electron charges. They have an effective mass which is approximately 10000 times lighter than the free electron mass. They are spatially extended over a few wave-lengths of light. Finally, they have an integer spin and obey the statistics of Bose-Einstein therefore. That is why, we expect that quadron-polaritons should be able to form a superfluid, i.e. roughly speaking, to unify their energies and velocities. Theoretically, because of the very light mass of quadron-polaritons, their condensation may happen even at room temperature in specially designed crystal structures. The superfluid of quadron-polaritons would be charged, that is why its creation is expected by us to lead to the phenomenon of superconductivity (circulation of current without any applied voltage). Observation of light-induced superconductivity would be an extraordinary discovery also having a considerable economic effect. We are going to pave the way towards this observation by complex theoretical and experimental studies of quadron-polaritons in ultrathin artificial crystal structures.