Blochsche

Blochsche is an adjectival form used in German-language physics to denote concepts named after the Swiss-American physicist Felix Bloch (1905–1983). The term appears in several foundational ideas across quantum mechanics, solid-state physics, and magnetic resonance, reflecting Bloch’s influence on how electrons behave in periodic structures and how spin systems evolve in magnetic fields.

Blochsches Theorem and Bloch functions: In a crystalline solid with a periodic potential, the electronic eigenfunctions can be written as a plane wave multiplied by a function with the lattice’s periodicity. This Bloch form underpins the concept of energy bands and crystal momentum. The associated Bloch function (or Bloch wave) is the periodic part that, together with the plane-wave factor, describes the electron’s state in the lattice.

Blochsche Gleichungen: The Bloch equations describe the time evolution of the magnetization vector in a magnetic field, used widely in Nuclear Magnetic Resonance (NMR) and magnetic resonance imaging (MRI). They include terms for relaxation processes that return the system to equilibrium.

Bloch-Siegert-Effekt: A frequency shift arising from counter-rotating terms when a spin system is driven strongly by an oscillating field. Named after Bloch and Siegert, the effect is important for high-precision spectroscopy and quantum control.

Bloch sphere: A geometric representation of the state of a two-level quantum system. Any pure state corresponds to a point on the surface of a unit sphere, providing an intuitive visualization of spin or qubit states.

Bloch waves and related concepts continue to be central in condensed matter physics, quantum optics, and spin dynamics, illustrating the lasting influence of Bloch’s work.