We consider a spin system coupled to a noisy environment via an interaction Hamiltonian $H$ which is a polynomial of degree $n$ in the spin operators $S_i$ ($n$-magnetic Hamiltonian), and show that the use of the quantum super-Zeno effect, in conjunction with a spin-anticoherent subspace, is highly effective in protecting the spin from the noise. When $n=1$, as in the case of unwanted rotations induced by stray magnetic fields, our scheme provides a quantum gyroscope, a concept that generalizes naturally to higher $n$ values (a quantum $n$-gyroscope). The gist of the proposed protocol is to use the quantum super-Zeno effect to confine a state to the subspace, and then exploit anticoherence to freeze its evolution within it.

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• Quantum Zeno dynamics
• Quantum control
• Quantum error correction
• Quantum information theory
• Quantum memories