There is an ongoing debate about the fundamental security of existing quantum key exchange schemes. This debate indicates not only that there is a problem with security but also that the meanings of perfect, imperfect, conditional and unconditional (information theoretic) security in physically secure key exchange schemes are often misunderstood. It has been shown recently that the use of two pairs of resistors with enhanced Johnsonnoise and a Kirchhoff-loop ‒ i.e., a Kirchhoff-Law-Johnson-Noise (KLJN) protocol ‒ for secure key distribution leads to information theoretic security levels superior to those of today’s quantum key distribution. This issue is becoming particularly timely because of the recent full cracks of practical quantum communicators, as shown in numerous peer-reviewed publications. The KLJN system is briefly surveyed here with discussions about the essential questions such as (i) perfect and imperfect security characteristics of the key distribution, and (ii) how these two types of securities can be unconditional (or information theoretical).

We present a new method for detecting and identifying bacteria by measuring impedance fluctuations (impedance noise) caused by ion release by the bacteria during phage infestation. This new method significantly increases the measured signal strength and reduces the negative effects of drift, material aging, surface imperfections, 1/f potential fluctuations, thermal noise, and amplifier noise. Comparing BIPIF with another well-known method, bacteria detection by SEnsing of Phage Triggered Ion Cascades (SEPTIC), we find that the BIPIF algorithm is easier to implement, more stable and significantly more sensitive (by several orders of magnitude). We project that by using the BIPIF method detection of a single bacterium will be possible.