Topological prethermal strong zero modes on superconducting processors.

Area of Science:

• Condensed Matter Physics
• Quantum Information Science
• Quantum Simulation

Background:

• Symmetry-protected topological phases lack local order parameters and are typically unstable at finite temperatures due to thermal excitations.
• Conventional understanding limits the stability of topological edge modes to zero temperature, restricting their practical applications.
• Disorder-free systems are crucial for robust quantum computation, but topological protection usually requires low temperatures.

Purpose of the Study:

• To observe and characterize a new type of topological edge mode protected by emergent symmetries.
• To demonstrate the persistence of these edge modes across the entire spectrum at finite temperatures.
• To explore the use of these topological edge modes as robust, long-lived qubits in a disorder-free system.

Main Methods:

• Digital quantum simulation of a one-dimensional disorder-free stabilizer Hamiltonian using an array of 100 programmable superconducting qubits.
• Observation of topological edge modes over extended periods (up to 30 cycles) for various initial states.
• Suppression of edge mode-bulk excitation interaction via dimerization of stabilizer strength, revealing emergent U(1)×U(1) symmetry.

Main Results:

• Observation of robust, long-lived topological edge modes protected by emergent symmetries, persisting across the spectrum at finite temperatures.
• Demonstration of persistent coherence in a logical Bell state prepared using these topological edge modes as qubits.
• Confirmation that edge mode stability is achievable in disorder-free systems even at finite temperatures.

Conclusions:

• The study establishes a viable digital simulation approach for studying topological matter at finite temperatures.
• Emergent symmetries and prethermal regimes enable the creation of robust, long-lived topological edge modes in disorder-free systems.
• These findings present a promising route for constructing robust boundary qubits for quantum computing applications.