Observation of parity-time symmetry breaking in a single spin system

Abstract

A fundamental axiom of quantum mechanics requires the Hamiltonians to be Hermitian which guarantees real eigen-energies and probability conservation. However, a class of non-Hermitian Hamiltonians with Parity-Time ($\mathcal{P}\mathcal{T}$) symmetry can still display entirely real spectra. The Hermiticity requirement may be replaced by $\mathcal{P}\mathcal{T}$ symmetry to develop an alternative formulation of quantum mechanics. A series of experiments have been carried out with classical systems including optics, electronics, microwaves, mechanics and acoustics. However, there are few experiments to investigate $\mathcal{P}\mathcal{T}$ symmetric physics in quantum systems.Here we report the first observation of the $\mathcal{P}\mathcal{T}$ symmetry breaking in a single spin system. We have developed a novel method to dilate a general $\mathcal{P}\mathcal{T}$ symmetric Hamiltonian into a Hermitian one, which can be realized in a practical quantum system.Then the state evolutions under $\mathcal{P}\mathcal{T}$ symmetric Hamiltonians, which range from $\mathcal{P}\mathcal{T}$ symmetric unbroken to broken regions, have been experimentally observed with a single nitrogen-vacancy (NV) center in diamond. Due to the universality of the dilation method, our result opens a door for further exploiting and understanding the physical properties of $\mathcal{P}\mathcal{T}$ symmetric Hamiltonian in quantum systems.

References in corpus (6)

• Making Sense of Non-Hermitian Hamiltonians
• Dynamic polarization of single nuclear spins by optical pumping of NV color centers in diamond at room temperature
• Observation of the exceptional point in cavity magnon-polaritons
• New topological invariants in non-Hermitian systems
• The Naimark dilated PT-symmetric brachistochrone
• Jarzynski equality in $\mathcal{P}\mathcal{T}$-symmetric quantum mechanics

Cited by in corpus (13)

• Topological Origin of Non-Hermitian Skin Effects
• Non-Hermitian Floquet topological phases: Exceptional points, coalescent edge modes, and the skin effect
• Quantum anomaly, non-Hermitian skin effects, and entanglement entropy in open systems
• Quantum sensing with a single-qubit pseudo-Hermitian system
• Diabolical Points in Coupled Active Cavities with Quantum Emitters
• Quantum information dynamics in a high-dimensional parity-time-symmetric system
• Stable States with Non-Zero Entropy under Broken $\mathcal{P}\mathcal{T}$-Symmetry
• Non-Hermitian Floquet phases with even-integer topological invariants in a periodically quenched two-leg ladder
• Observation of two PT transitions in an electric circuit with balanced gain and loss
• Floquet exceptional contours in Lindblad dynamics with time-periodic drive and dissipation
• Balanced gain and loss in spatially extended non-$\mathcal{P}\mathcal{T}$-symmetric multi-well potentials
• Resonant-amplified and invisible Bragg scattering based on spin coalescing modes
• Scattering of Spin-$\frac{1}{2}$ Particles from a $\mathcal{P}\mathcal{T}$-symmetric Complex Potential