Bits and Qubits

Ray LaPierre

Masataka Ohta

While Shannon introduced “binary digits, or more briefly bits” as units of information, a binary digit (and, thus, a bit) originally and still means a character of “0” or “1”, which may be represented by a binary symbol or storage cell. As a result, a bit often means a binary symbol or storage cell, which is inherited by a “qubit”, a quantum bit, introduced by Schumacher as “the fundamental units of quantum information”. Schumacher himself uses a bit, not a qubit, as a unit of quantum information and a qubit is a quantum binary symbol or storage cell.

Chuan-Ming Li, Tzonelih Hwang

Due to the high cost of the qubit generating device (QGD) (the single photon source), QGD may not be available at the same time in both communicating parties (Alice and Bob) who have to execute the quantum bit string commitment (QBSC) protocol for some application environments. All the existing QBSC protocols allow one-way commitment i.e., only the party (Bob) who possesses the QGD is allowed to commit a bit string to Alice who does not have the QGD, but not the other way around. However, what happens if Alice, who does not have the QGD, is required to commit a bit string to Bob? The current QBSC protocols fail to provide a solution in this case. Therefore, the purpose of this paper is to allow Alice, who is not equipped with the QGD, to commit a bit string to Bob who has the QGD. With our proposed protocol, together with previously proposed QBSC protocols, Alice and Bob can perform two-way commitment, even though Bob is the only party who is equipped with the QGD.

Abdulla M. Abu-ayyash, Naim Ajlouni

Practical quantum key distribution gain is usually less than the theoretical limit, this is due to the imperfection of physical devices, quantum channels, and the lost qubits due to test carried out for for the identification of the presence of an eavesdropper and the consequence reduction of obtained knowledge. In this paper a technique is presented to recover some of the unused qubits which result in an increase in the gain of the QKD protocols, in this research it was found that for the BB84 the recovered qubits can be as much as 11% of the initial key bits. This technique is based on discovering the relationship between the initial key bits and the original random bits which will aid in the recovery process of the unused qubits ( unused qubits are the bits which are assumed to be lost at the start of the process due to the random process and for BB84 it is assumed to be around 50% of the generated key bits).