[论文解读] Conditions for stimulated emission in anomalous gravity-superconductors interactions

Giovanni Modanese, Timo Junker|ArXiv.org|Aug 19, 2009

Cosmology and Gravitation Theories参考文献 9被引用 6

一句话总结

本文通过将YBCO等层状超导体建模为本征约瑟夫森结阵列，研究了其在受激引力辐射发射中的条件。采用带有振荡输运电流连续泵浦的改进Frantz-Nodvik方程，发现即使A和B系数异常偏大（可能源于量子引力效应），受激发射仍因IV功率较低而受到极大限制，表明此类系统中可观测引力辐射的可行性条件极为严苛。

ABSTRACT

Several authors have studied the generation of gravitational fields by condensed-matter systems in non-extreme density conditions. General Relativity and lowest-order perturbative Quantum Gravity predict in this case an extremely small emission rate, so these phenomena can become relevant only if some strong quantum effect occurs. Quantum aspects of gravity are still poorly understood. It is believed that they could play a role in systems which exhibit macroscopic quantum coherence, like superconductors and superfluids, leading to an "anomalous" coupling between matter and field. We mention here recent work in this field by Woods, Chiao, Becker, Agop et al., Ummarino, Kiefer and Weber. New results are presented concerning anomalous stimulated gravitational emission in a layered superconductor like YBCO. We model the superconductor as an array of intrinsic Josephson junctions. The superconducting parameters are defined by our preliminary measurements with melt-textured samples. We write explicitly and solve numerically the Josephson equations which give the normal and super components of the total current in the superconductor, and derive from this the total available power P=IV. Then, assuming that the coefficients A and B for spontaneous and stimulated gravitational emission are known, we apply to this case the Frantz-Nodvik equation for a laser amplifier. The equation is suitably modified in order to allow for a "continuous pumping" given by an oscillating transport current. The conclusions are relevant for the evaluation of gravitational emission from superconductors. We find that even if the A and B coefficients are anomalously large (possibly because of the Quantum Gravity effects mentioned above), the conditions for stimulated emission are quite strict and the emission rate strongly limited by the IV value.

研究动机与目标

• 探究在异常物质-场耦合条件下，超导体中受激引力辐射发射的可行性。
• 解决广义相对论预测非极端密度凝聚态系统中引力辐射可忽略不计的挑战。
• 评估超导体中的宏观量子相干性是否可通过量子引力效应增强引力辐射发射。
• 将超导体建模为本征约瑟夫森结阵列，以计算可用功率和发射条件。
• 通过振荡输运电流的连续泵浦，评估引力辐射发射的实际限制。

提出的方法

• 将超导体建模为本征约瑟夫森结堆叠，以模拟宏观量子相干性。
• 数值求解约瑟夫森方程，以确定正常电流和超电流分量。
• 根据I-V特性计算总可用功率P = IV。
• 应用改进的Frantz-Nodvik方程，以描述引力辐射的激光式放大。
• 为连续泵浦（通过振荡输运电流）调整该方程。
• 假设已知的A和B系数以描述自发与受激发射，评估发射阈值。

实验结果

研究问题

• RQ1 在YBCO等层状超导体中，受激引力辐射发射在何种条件下可能发生？
• RQ2 宏观量子相干性的存在如何影响物质与引力场之间的耦合？
• RQ3 通过振荡电流实现的连续泵浦在促进或限制受激发射中起什么作用？
• RQ4 引力辐射的A和B系数如何影响可观测发射的可行性？
• RQ5 发射速率在多大程度上受系统中可用IV功率的限制？

主要发现

• 即使A和B系数异常偏大（可能源于量子引力效应），受激引力辐射发射仍受到强烈抑制。
• 发射速率强烈受限于可用功率P = IV，而该功率受约瑟夫森结阵列的I-V特性约束。
• 带有连续泵浦的改进Frantz-Nodvik方程表明，在实际实验条件下，受激发射的阈值极难达到。
• 该模型表明，可观测引力辐射的发射需要极高的电流密度，或不切实际地巨大的A和B系数。
• 结果表明，若无耦合或功率输入的显著增强，超导体中异常引力辐射的探测可能性极低。