6 papers
Entangled Quantum Clocks for Measuring Proper-Time Difference
W. Y. Hwang, D. Ahn, S. W. Hwang +1
We report that entangled pairs of quantum clocks (non-degenerate quantum bits) can be used as a specialized detector for precisely measuring difference of proper-times that each co…
Quantum Gambling Using Two Nonorthogonal States
W. Y. Hwang, D. Ahn, S. W. Hwang
We give a (remote) quantum gambling scheme that makes use of the fact that quantum nonorthogonal states cannot be distinguished with certainty. In the proposed scheme, two particip…
Eavesdropper's Optimal Information in Variations of Bennett-Brassard 1984 Quantum Key Distribution in the Coherent Attacks
W. Y. Hwang, D. Ahn, S. W. Hwang
We calculate eavesdropper's optimal information on raw bits in Bennett-Brassard 1984 quantum key distribution (BB84 QKD) and six-state scheme in coherent attacks, using a formula b…
Efficient Schemes for Reducing Imperfect Collective Decoherences
W. Y. Hwang, H. J. Lee, D. Ahn +1
We propose schemes that are efficient when each pair of qubits undergoes some imperfect collective decoherence with different baths. In the proposed scheme, each pair of qubits is…
Correlated Errors in Quantum Error Corrections
W. Y. Hwang, D. Ahn, S. W. Hwang
We show that errors are not generated correlatedly provided that quantum bits do not directly interact with (or couple to) each other. Generally, this no-qubits-interaction conditi…
Quantum Cryptography without Public Announcement of Bases
Won Young Hwang, In Gyu Koh, Yeong Deok Han
This paper provides a simple variation of the basic ideas of the BB84 quantum cryptographic scheme leading to a method of key expansion. A secure random sequence (the bases sequenc…