In their paper titled "Theory of shot noise in strange metals," Alexander Nikolaenko, Subir Sachdev, and Aavishkar A. Patel extend the theory of shot noise to strange metals that lack quasiparticle excitations. This extension requires a generalization of the Boltzmann equation with a noise source to distribution functions that independently depend on both excitation momentum and energy. The authors apply this theory to a model of a strange metal with linear resistivity in temperature ($T$). The model describes a Fermi surface with a spatially random Yukawa coupling to a critical boson. They find that the Fano factor, which characterizes the suppression or enhancement of shot noise relative to Poisson statistics, is suppressed in the strange metal compared to diffusive metals with quasiparticles. At low temperatures, they obtain a Fano factor equal to $1/6$, contrasting with the $1/3$ Fano factor observed in diffusive metals. The study also explores the dependence of shot noise on temperature and applied voltage in the strange metal model. The authors note that their results are generally consistent with recent observations by Chen et al. (arXiv:2206.00673). Furthermore, they compare their random Yukawa model to quasi-elastic electron-phonon scattering, which also generates linear resistivity in temperature ($T$). They argue that shot noise observations can serve as a useful diagnostic tool for distinguishing between these two mechanisms. Overall, this paper presents an extended theory of shot noise in strange metals without quasiparticle excitations and applies it to a specific model describing a Fermi surface coupled to critical bosons. The findings highlight the suppression of the Fano factor in strange metals and provide insights into how shot noise depends on temperature and applied voltage. Additionally, the study suggests that shot noise measurements can help differentiate between different mechanisms contributing to linear resistivity in temperature.
In strange metals, there is a type of noise called shot noise. Scientists have developed a theory to understand this noise. They used an equation called the Boltzmann equation and added a source of noise to it. This equation helps them understand how the distribution of something called momentum and energy affects the noise. They applied this theory to a model of a strange metal that has a special kind of resistance that changes with temperature. They found that the shot noise in strange metals is different from other metals with particles called quasiparticles. The shot noise in strange metals is smaller than in other metals at low temperatures. The scientists also studied how the shot noise changes with temperature and voltage in their model of strange metal. Their findings match what other scientists have observed recently. They compared two different models for explaining the special resistance in strange metals using shot noise as a tool."
Definitions
- Shot Noise: A type of random variation or fluctuations in electrical current.
- Strange Metals: A special type of material that has unusual properties, such as its resistance changing with temperature.
- Boltzmann Equation: An equation used by scientists to describe how particles move and distribute their energy.
- Momentum: A property of moving objects that determines how much force is needed to change their motion.
- Energy: The ability to do work or make things happen.
- Resistance: A measure of how difficult it is for electricity to flow through a material.
- Quasiparticles: Particles that behave like electrons but are not actually
Exploring Shot Noise in Strange Metals
Strange metals are a class of materials that lack quasiparticle excitations and exhibit linear resistivity in temperature ($T$). In their paper titled "Theory of shot noise in strange metals," Alexander Nikolaenko, Subir Sachdev, and Aavishkar A. Patel extend the theory of shot noise to these materials. This extension requires a generalization of the Boltzmann equation with a noise source to distribution functions that independently depend on both excitation momentum and energy. The authors apply this theory to a model of a strange metal with linear resistivity in temperature ($T$) and explore how shot noise depends on temperature and applied voltage.
Extending the Theory of Shot Noise
The authors begin by extending the theory of shot noise to strange metals without quasiparticle excitations. To do so, they generalize the Boltzmann equation with an additional source term for thermal fluctuations. This new equation describes distribution functions that independently depend on both excitation momentum and energy.
Applying Theory to Model System
Next, they apply this extended theory to a model system describing a Fermi surface coupled to critical bosons via spatially random Yukawa couplings. By studying this model system, they find that the Fano factor (which characterizes suppression or enhancement relative to Poisson statistics) is suppressed compared to diffusive metals with quasiparticles at low temperatures - specifically, it is equal to $1/6$, contrasting with the $1/3$ Fano factor observed in diffusive metals. Furthermore, they explore how shot noise depends on temperature and applied voltage in this model system.
Comparison With Other Mechanisms
The authors also compare their random Yukawa model system with quasi-elastic electron-phonon scattering which also generates linear resistivity in temperature ($T$). They argue that shot noise observations can serve as useful diagnostic tools for distinguishing between these two mechanisms since each produces distinct results when examined through measurements such as those used here.
Conclusion
Overall, this paper presents an extended theory of shot noise applicable to strange metals without quasiparticle excitations and applies it specifically to one particular model describing a Fermi surface coupled randomly via Yukawa couplings with critical bosons. The findings highlight the suppression of the Fano factor at low temperatures compared to diffusive metals as well as provide insights into how shot noise depends on temperature and applied voltage within this specific context.. Additionally, it suggests that measuring shot noise may be useful for differentiating between various mechanisms contributing towards linear resistivity in temperature - something which could prove invaluable for further research into strange metals going forward
We extend the theory of shot noise in coherent metals to shot noise in strange metals without quasiparticle excitations. This requires a generalization of the Boltzmann equation with a noise source to distribution functions which depend independently on the excitation momentum and energy. We apply this theory to a model of a strange metal with linear in temperature ($T$) resistivity, describing a Fermi surface with a spatially random Yukawa coupling to a critical boson. We find a suppression of the Fano factor in the strange metal, and describe the dependence of the shot noise on temperature and applied voltage. At low temperatures, we obtain a Fano factor equal to $1/6$, in contrast to the $1/3$ Fano factor in diffusive metals with quasiparticles. Our results are in general agreement with recent observations by Chen et al. (arXiv:2206.00673). We further compare the random Yukawa model to quasi-elastic electron-phonon scattering that also generates $T$-linear resistivity, and argue that shot noise observations offer a useful diagnostic to distinguish between them.
