Conditions for superdecoherence

Abstract

Decoherence is the main obstacle to quantum computation. The decoherence rate per qubit is typically assumed to be constant. It is known, however, that quantum registers coupling to a single reservoir can show a decoherence rate per qubit that increases linearly with the number of qubits. This effect has been referred to as superdecoherence, and has been suggested to pose a threat to the scalability of quantum computation. Here, we show that superdecoherence is absent when the spectrum of the single reservoir is continuous, rather than discrete. The reason of this absence, is that, as the number of qubits is increased, a quantum register inevitably becomes susceptible to an ever narrower bandwidth of frequencies in the reservoir. Furthermore, we show that for superdecoherence to occur in a reservoir with a discrete spectrum, one of the frequencies in the reservoir has to coincide exactly with the frequency the quantum register is most susceptible to. We thus fully resolve the conditions that determine the presence or absence of superdecoherence. We conclude that superdecoherence is easily avoidable in practical realizations of quantum computers.

arXiv comment20 pages, 6 figures, quantum journal accepted version

References in corpus (31)

• Quantum Computing in the NISQ era and beyond
• Supplementary information for "Quantum supremacy using a programmable superconducting processor"
• Quantum-enhanced measurements: beating the standard quantum limit
• Quantum metrology
• Decoherence Free Subspaces for Quantum Computation
• Noiseless Quantum Codes
• 14-qubit entanglement: creation and coherence
• Observation of a Many-Body Dynamical Phase Transition with a 53-Qubit Quantum Simulator
• Quantum Computers and Dissipation
• Continuous variable quantum information: Gaussian states and beyond
• Maintaining coherence in Quantum Computers
• Preserving coherence in quantum computation by pairing quantum bits
• Theory of Decoherence-Free Fault-Tolerant Universal Quantum Computation
• Decoherence-Free Subspaces and Subsystems
• Numerical Renormalization Group for Bosonic Systems and Application to the Subohmic Spin-Boson Model
• Reducing decoherence in quantum computer memory with all quantum bits coupling to the same environment
• Decoherence of quantum registers
• Quantum phase transitions in the sub-ohmic spin-boson model: Failure of the quantum-classical mapping
• Equilibrium and non-equilibrium dynamics of the sub-ohmic spin-boson model
• Error Avoiding Quantum Codes
• On the spin--boson model with a sub--Ohmic bath
• Coherence trapping and information back-flow in dephasing qubits
• Quantum probes for the cutoff frequency of Ohmic environments
• Collective decoherence of cold atoms coupled to a Bose-Einstein condensate
• Microscopic description for the emergence of collective dissipation in extended quantum systems
• Pure dephasing in flux qubits due to flux noise with spectral density scaling as $1/f^{\alpha }$
• Incomplete pure dephasing of N-qubit entangled W states
• Effective dephasing for a qubit interacting with a transverse classical field
• Decoherence in a N-qubit solid-state quantum computer
• Scaling of Decoherence Effects in Quantum Computers
• Dynamical fidelity susceptibility of decoherence-free subspaces

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• Quantum metrology with one auxiliary particle in a correlated bath and its quantum simulation
• Thermometry by correlated dephasing of impurities in a 1D Fermi gas
• Extreme depolarization for any spin
• Revealing correlated noise with single-qubit operations