Quantifying the photocurrent fluctuation in quantum materials by shot noise

Area of Science:

• Condensed Matter Physics
• Quantum Materials Science
• Materials Characterization

Background:

• DC photocurrent is a known method for characterizing quantum materials lacking inversion symmetry.
• The limitations of photocurrent measurements necessitate alternative diagnostic techniques for quantum materials.

Purpose of the Study:

• To propose and theoretically develop DC shot noise (DSN) as a novel diagnostic tool for quantum materials.
• To explore the potential of DSN in revealing the topology and geometry of quantum materials, including those with inversion symmetry.

Main Methods:

• Developed a quantum theory for DC shot noise (DSN) in gapped quantum systems.
• Categorized DSN into shift and injection components based on photocurrent operator contributions.
• Investigated symmetry constraints (inversion and time-reversal) on DSN, considering light polarization.

Main Results:

• Demonstrated that DSN is not forbidden by inversion symmetry, unlike photocurrent.
• Showed that DSN encodes geometrical properties of Bloch electrons, including Berry curvature and quantum metric.
• Calculated DSN in monolayer GeS and bilayer MoS2, finding larger DSN in centrosymmetric phases.

Conclusions:

• DC shot noise (DSN) offers a versatile method for probing quantum material properties, complementary to photocurrent.
• DSN provides unique insights into material topology and geometry, overcoming limitations of inversion symmetry.
• The developed theory and applications highlight DSN's potential for characterizing diverse quantum materials.