Abstract Quantum teleportation transfers an unknown qubit state from a sender to a receiver using a shared entangled pair and a classically conditioned correction without moving the physical carrier. On the dynamic-circuit hardware, the complete protocol (which includes mid-circuit measurement and conditional feedforward) now runs on a single circuit. We use this to benchmark three-qubit teleportation on a 156-qubit IBM Heron r2 processor (ibm_fez). A single-qubit RY(θ) input was teleported at six angles along a meridian of the Bloch sphere and reconstructed by state tomography alongside two ablation controls; one without entanglement and the other without feedforward. The full protocol returns a mean fidelity of about 0.945, nearly constant across the angles and above the 2/3 full-Bloch-sphere reference at all six sampled angles. Removing feedforward lowered the fidelity to about 0.51, close to a maximally mixed state. On the other hand, removing entanglement yields (1 + cos²θ)/2 with a mean near 0.75, transferring the population but losing the coherence. Together, these results establish that entanglement and feedforward are both necessary. The calibration-limited fidelity serves as a reference for this class of hardware. A separate run returned a Bell-state fidelity value of 0.957. A branch-resolved analysis confirmed that the four measurement branches are Pauli rotations of the target realigned by feedforward. The reported fidelity depends only on the rotation angle and the device noise.
Abstract Quantum teleportation transfers an unknown qubit state from a sender to a receiver using a shared entangled pair and a classically conditioned correction without moving the physical carrier. On the dynamic-circuit hardware, the complete protocol (which includes mid-circuit measurement and conditional feedforward) now runs on a single circuit. We use this to benchmark three-qubit teleportation on a 156-qubit IBM Heron r2 processor (ibm_fez). A single-qubit RY(θ) input was teleported at six angles along a meridian of the Bloch sphere and reconstructed by state tomography alongside two ablation controls; one without entanglement and the other without feedforward. The full protocol returns a mean fidelity of about 0.945, nearly constant across the angles and above the 2/3 full-Bloch-sphere reference at all six sampled angles. Removing feedforward lowered the fidelity to about 0.51, close to a maximally mixed state. On the other hand, removing entanglement yields (1 + cos²θ)/2 with a mean near 0.75, transferring the population but losing the coherence. Together, these results establish that entanglement and feedforward are both necessary. The calibration-limited fidelity serves as a reference for this class of hardware. A separate run returned a Bell-state fidelity value of 0.957. A branch-resolved analysis confirmed that the four measurement branches are Pauli rotations of the target realigned by feedforward. The reported fidelity depends only on the rotation angle and the device noise.
The five-qubit Absolutely Maximally Entangled AME(5,2) state, whose every pair of qubits is maximally mixed so that all its information lives in non-local correlations, could in principle serve as a single shared quantum networking resource for teleporting two unknown qubits in parallel (each via its own Bell measurement and Pauli correction). Nonetheless, its hardware implementations remain scarce despite its theoretical importance. Here, we demonstrate parallel teleportation based on a five-qubit absolutely maximally entangled state, AME(5,2), on the superconducting processor ibm_pittsburgh. We construct three-qubit Clifford decoders that extract two Bell pairs using three logical two-qubit gates for each of 60 inequivalent sender-receiver assignments. Using parallelization and classical Pauli frame post-processing, we retain reference-receiver entanglement on both channels after three teleportation rounds. With XY4 dynamical decoupling and the lowest-cost decoder, the final entanglement fidelities are 0.704±0.028 and 0.680±0.022, where uncertainties are pointwise 99% confidence-interval half-widths over eight trials. Their lower bounds exceed the separability threshold of 1/2. The decoder with lower circuit depth generally retains higher mean fidelity, and XY4 generally improves on XX. These results establish a hardware demonstration of two-channel entanglement transmission through repeated AME-assisted teleportation and provide compact decoding circuits for reconfigurable multipartite communication.
Quantum information can not be perfectly cloned, but approximate copies of quantum information can be generated. Quantum telecloning combines approximate quantum cloning, more typically referred as quantum cloning, and quantum teleportation. Quantum telecloning allows approximate copies of quantum information to be constructed by separate parties, using the classical results of a Bell measurement made on a prepared quantum telecloning state. Quantum telecloning can be implemented as a circuit on quantum computers using a classical co-processor to compute classical feed forward instructions using if statements based on the results of a mid-circuit Bell measurement in real time. We present universal, symmetric, optimal1→Mtelecloning circuits, and experimentally demonstrate these quantum telecloning circuits forM=2up toM=10, natively executed with real time classical control systems on IBM Quantum superconducting processors, known as dynamic circuits. We perform the cloning procedure on many different message states across the Bloch sphere, on 7 IBM Quantum processors, optionally using the error suppression technique X-X sequence digital dynamical decoupling. Two circuit optimizations are utilized, one which removes ancilla qubits forM=2,3, and one which reduces the total number of gates in the circuit but still uses ancilla qubits. Parallel single qubit tomography with MLE density matrix reconstruction is used in order to compute the mixed state density matrices of the clone qubits, and clone quality is measured using quantum fidelity. These results present one of the largest and most comprehensive NISQ computer experimental analyses on (single qubit) quantum telecloning to date. The clone fidelity sharply decreases to 0.5 forM>5, but forM=2we are able to achieve a mean clone fidelity of up to 0.79 using dynamical decoupling.
We present a density-matrix simulation framework for quantum teleportation that integrates a comprehensive set of physically motivated noise channels calibrated to contemporary superconducting processors. Departing from deferred-measurement simplifications, the simulator explicitly tracks measurement branches of the Bell measurement and models realistic effects, including readout misassignment, coherent control errors, leakage, crosstalk, and low-frequency dephasing. The framework produces an end-to-end error budget and is validated against experimental executions, with extensive statistical checks (bootstrap confidence intervals, hypothesis tests, and goodness-of-fit analysis) demonstrating close agreement between predicted and measured state-transfer behavior. Our analysis highlights readout misassignment as the dominant fidelity limiter in the measurement-based protocol and shows that targeted readout mitigation provides higher leverage than equivalent improvements in coherence alone. The implementation is extensible to multi-qubit and networked teleportation protocols and serves as a practical tool for forecasting teleportation performance on near-term quantum hardware.
Quantum entanglement is one of the primary features which distinguish quantum computers from classical computers. In gate-based quantum computing, the creation of entangled states or the distribution of entanglement across a quantum processor often requires circuit depths, which grow with the number of entangled qubits. However, in teleportation-based quantum computing, one can deterministically generate entangled states with a circuit depth that is constant in the number of qubits, provided that one has access to an entangled resource state, the ability to perform mid-circuit measurements, and can rapidly transmit classical information. In this work, aided by fast classical field programmable gate array-based control hardware with a feedback latency of only 150 ns, we explore the utility of teleportation-based protocols for generating non-local, multi-partite entanglement between superconducting qubits. First, we demonstrate well-known protocols for generating Greenberger–Horne–Zeilinger states and non-local controlled-NOT gates in constant depth. Next, we utilize both protocols for implementing a quantum fan-out gate in constant depth among three non-local qubits (i.e., controlled-NOT-NOT). Finally, we demonstrate deterministic state teleportation and entanglement swapping between qubits on opposite sides of our quantum processor. Throughout this work, we find that the fidelity of our teleportation-based protocols is limited by measurement-induced dephasing on idling spectator qubits. Therefore, our work serves as a useful study of the current benefits and limitations of teleportation-based protocols on contemporary superconducting quantum processors.
FINDING: Quantum energy teleportation demonstrated on superconducting hardware, transferring physical quantities (not just information) across remote locations. | MATH: Key equation from arXiv:2301.02666v5 — the teleported energy expectation value ⟨E⟩ = ⟨ψ|H_B|ψ⟩ where H_B is the receiver's Hamiltonian, with fidelity F ≥ 0.99. The protocol uses a shared entangled state |Φ⟩ = (|00⟩ + |11⟩)/√2 and local operations U_A(θ) = exp(-iθσ_x/2) with θ tuned to maximize energy transfer. | CONNECTION: The optimal energy transfer occurs at specific phase angles θ = π/2, 3π/2 — multiples of π/2, reflecting 90° rotational symmetry in the Bloch sphere, analogous to crystallographic 4-fold symmetry. No direct golden ratio or base-60 link; the key ratio is the entanglement fraction 1/√2 ≈ 0.707, which is the cosine of 45° (π/4), a fundamental symmetry angle. | DEPTH: 7 — This is a first experimental realization of energy teleportation, confirming theoretical predictions from 2008 (Hotta). It advances un Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com
FINDING: Quantum teleportation is a protocol for transferring an unknown quantum state via shared entanglement and classical communication — not a transport of matter/energy. | MATH: Bell basis: {|Φ⁺⟩, |Φ⁻⟩, |Ψ⁺⟩, |Ψ⁻⟩} = (1/√2)(|00⟩ ± |11⟩), (1/√2)(|01⟩ ± |10⟩). Teleportation circuit: CNOT + Hadamard + 2 classical bits → Pauli correction {I, X, Z, XZ}. State transfer fidelity = 1 (ideal), requires 2 ebits + 2 cbits per qubit. | CONNECTION: Bell states form an orthonormal basis in ℂ²⊗ℂ² — a 4D root system isomorphic to D₂ (dihedral symmetry, order 8). The CNOT+Hadamard sequence corresponds to a Clifford group element, whose action on the Pauli group preserves the symplectic structure over GF(2)² — a lattice symmetry (square lattice, Z²). The 2-bit classical correction maps to the four Pauli operators, which are the vertices of a tetrahedron in the Bloch sphere — a crystallographic point group (T_d, order 24). The ratio 1/√2 appears in all Bell states — this is the cosine of 45°, linkin Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com